#geometry-and-trigonometry | Mathematics | Page 254

crisp grove Mar 4, 2020, 7:07 PM

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see at the top of the cylinder

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I mean the measure for the thickness is on the bottom

glacial wharf Mar 5, 2020, 2:50 AM

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I need some help with this shit

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I forgot what theorem i need to use for this type of problem

📎 image0.jpg

upper karma Mar 5, 2020, 4:06 AM

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is it necessary i learn the csc, cot, sec identities for an end of year trig test im taking soon?

languid ingot Mar 5, 2020, 4:40 AM

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i would just learn everything my teacher taught me

upper karma Mar 5, 2020, 5:15 AM

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What kind of parametric equation, in polar coordinate system, would describe the motion of - like, a motorcycle on a tiny planet that is racing forward with just a little turn?

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does anyone know a good youtube video

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that reviews the whole trignometry part

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Whats "the whole trigonometry part" ?

summer spire Mar 5, 2020, 6:03 AM

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@upper karma wouldn't that just be a circle of a certain diameter on a sphere?

upper karma Mar 5, 2020, 6:05 AM

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If the velocity matched the angle so that its end position is its start, then yes.

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lets just say its a constant 1 degree angle

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@summer spire (someone else told me that this is a differential equation - I am hoping this isn't true 😬 )

summer spire Mar 5, 2020, 6:09 AM

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beyond plotting a circle, I'm not even entirely sure what you're asking for tbh

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the effect of the angle of the wheels would depend on the wheelbase and the size of the planet, but so long as everything is constant (speed, angle, etc) it doesn't sound super complicated

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actually I don't even think speed would make a difference

rich wolf Mar 5, 2020, 6:12 AM

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Bro go engineer elsewhere

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This is math server real problems dont matter

opaque spade Mar 5, 2020, 3:38 PM

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Anyone available

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For

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A quick Geo help question. Thing

dire rampart Mar 5, 2020, 3:58 PM

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justask

upper karma Mar 5, 2020, 5:03 PM

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I need help 😭

📎 Screen_Shot_2020-03-05_at_9.01.34_AM.png

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Im confused on what two possibles angles for angle B

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I thought sinB is basically the angle and to find the other angle you inverse sin .77148 but it says it's incorrect and i don't understand

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someone pls help :9

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😭 *

languid ingot Mar 5, 2020, 5:37 PM

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the inverse sin cannot find an obtuse angle, instead it'll always give the supplementary acute angle

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So arcsin of .77148 is 50.48697821132838, then other one will be 180 - 50.48697821132838 i think

vale nimbus Mar 5, 2020, 8:00 PM

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isnt it cuz sin(A) = sin(180°-A)

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so they're just asking for the supplementairy angle

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@upper karma

upper karma Mar 5, 2020, 8:33 PM

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@languid ingot was right i got it right but i'm not sure how to find c2

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📎 Screen_Shot_2020-03-05_at_12.34.01_PM.png

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i used law of sines ( Sin angle B / side b = Sin angle C / side c )and got sin129.51/241.5 = sin14/c

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then i crossed multiplied and got 241.5sin(14/sin(129.51

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and that gave me 75.7266 but it says its wrong

silent plank Mar 5, 2020, 8:57 PM

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probably rounding errors or something

upper karma Mar 5, 2020, 9:04 PM

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oh yeah it was i rounded up angle C 2

fringe cipher Mar 5, 2020, 11:33 PM

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Show that the distance of any point on the equilateral hyperbola x² - y² = a² to the center is the mean proportional between the focal radii.
can someone help me show that?
something that might help is that from geometry, m is the mean proportional of p and iff p/m = m/q

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iff = if and only if btw

stark ferry Mar 6, 2020, 2:36 AM

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How do you do this?

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📎 image0.png

weak shoal Mar 6, 2020, 2:37 AM

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Draw a picture first

stark ferry Mar 6, 2020, 2:44 AM

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Ok

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What next

weak shoal Mar 6, 2020, 2:53 AM

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Show your diagram

stark ferry Mar 6, 2020, 2:57 AM

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I can’t send pictures on my phone :/

fringe cipher Mar 6, 2020, 3:38 AM

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pls someone help 😦

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Show that the distance of any point on the equilateral hyperbola x² - y² = a² to the center is the mean proportional between the focal radii.
can someone help me show that?
something that might help is that from geometry, m is the mean proportional of p and iff p/m = m/q
iff = if and only if btw

meager spruce Mar 6, 2020, 4:43 AM

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📎 image0.jpg

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Any help with this would be great

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I need to get this one done so I can 😴

winged zinc Mar 6, 2020, 10:00 AM

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@meager spruce

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I can help

peak hound Mar 6, 2020, 1:44 PM

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📎 20200306_073447.jpg

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Teacher explains literally nothing and I'm left on the dark on how this works

brave zephyr Mar 6, 2020, 1:57 PM

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@stark ferry Lol are you using Canvas?

proper citrus Mar 6, 2020, 2:16 PM

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Is there a way to simplify $tan^{-1} (\frac {tan \theta }{e})$

somber coyoteBOT Mar 6, 2020, 2:16 PM

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Tāhā:

📎 424633184505036802.png

proper citrus Mar 6, 2020, 2:20 PM

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e is an arbitrary constant

dark sparrow Mar 6, 2020, 2:33 PM

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no

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there is not

stark ferry Mar 6, 2020, 3:01 PM

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@brave zephyr yes

brave zephyr Mar 6, 2020, 3:02 PM

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Do you live in Howard County?

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That’s what we use for assessments

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And Homework’s

stark ferry Mar 6, 2020, 3:28 PM

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Nope I’m down south in corpus

night hinge Mar 6, 2020, 3:36 PM

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Are we allowed to post textbooks questions?

twin prawn Mar 6, 2020, 4:41 PM

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yes

upper karma Mar 6, 2020, 6:10 PM

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Question: Lets say you're a bike rider, and you start out at 0,0 - and you pedel forward (y+), but keep a constant turn of 1 degree to the right (x+) ----- what is the radius of the circle you will eventually create?

tribal wind Mar 6, 2020, 6:19 PM

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http://www.davdata.nl/math/turning_radius.html

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@upper karma

upper karma Mar 6, 2020, 6:27 PM

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ok, what if its just a particle, and not a 2 wheeled object?

tribal wind Mar 6, 2020, 6:28 PM

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then it's ill-defined, you need a length to have something like a 1-degree turned steering wheel

summer spire Mar 6, 2020, 6:36 PM

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still trying to make sense of the bike turning radius, huh? megathink
the form of the question changed since I last saw it

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curious what you're trying to work this out for

upper karma Mar 6, 2020, 6:40 PM

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Yeah, it was this: imagine that you're a motorcyle on a tiny planet. is there a parametric equation in spherical coordinates (I think that'd be the easiest) to describe the motion of the bike at a constant 1 degree turn?

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depends on the size of the planet and the speed of the bike I know .... but

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I was trying to generalize it into the flat plane, and I'm still confused

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because if I keep a constant 1 degree turn ---- well, its going to get into calculus here

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lets say for each step forward, I then turn 1 degree - so that my path looks like a giant 360 faced polygon

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well, a step forward then turn isn't CONSTANT - so, I reduce the step size - which reduces the radius

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until - the step size is zero, so that the turn is CONSTANT, but then the circle is zero

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😖 😕

upper karma Mar 6, 2020, 11:51 PM

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You want this, no? https://en.wikipedia.org/wiki/Great-circle_distance

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📎 unknown.png

karmic swallow Mar 7, 2020, 2:42 AM

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anyone on

rich wolf Mar 7, 2020, 4:15 AM

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Is there a number system where |z|<0 can be true

dark sparrow Mar 7, 2020, 4:46 AM

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no

rich wolf Mar 7, 2020, 5:10 AM

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@dark sparrow pls

dark sparrow Mar 7, 2020, 5:11 AM

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why are you so desperate tho

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why do you NEED negative absolute values

rich wolf Mar 7, 2020, 5:12 AM

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I want to define negative lengths

dark sparrow Mar 7, 2020, 5:13 AM

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for what

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are you allergic to the triangle inequality or sth

rich wolf Mar 7, 2020, 5:13 AM

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Just in general

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Having negative (and nonreal) lengths

dark sparrow Mar 7, 2020, 5:15 AM

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why do you need that

rich wolf Mar 7, 2020, 5:16 AM

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📎 9eee089db338c4aacd99f787d816871f.png

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To do this

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Not trolling i swear

tribal wind Mar 7, 2020, 5:17 AM

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minkowski space is kindaaaa like that

fringe dirge Mar 7, 2020, 8:00 AM

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triangle inequality is just going to be ruined

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if you allow |z| < 0

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and triangle inequality is like the thing that makes metric spaces what they are

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otherwise you'd get just crazy spaces

sly marlin Mar 7, 2020, 11:04 AM

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Hmm, but using complex numbers, letting the sides be complex and hypotenuse be real, |(a+bi)(a-bi)|=c^2, which if we generalise a, bi to complex numbers, we are using two complex numbers to represent the direction of the sides of the triangle, which hmm...

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c here is just $|b-a|$ which is $\sqrt{(b-a)(\overline{b-a})}$

📎 triangle.png

somber coyoteBOT Mar 7, 2020, 11:05 AM

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Element118:

📎 104219409991626752.png

sly marlin Mar 7, 2020, 11:06 AM

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too bad complex conjugates just behave weirdly

floral harbor Mar 7, 2020, 11:06 AM

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📎 Screenshot_20200307_120538_org.edx.mobile.jpg

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Is it correct?

sly marlin Mar 7, 2020, 11:06 AM

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it's a circle with radius 2

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do you know what tan means?

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@floral harbor

floral harbor Mar 7, 2020, 11:07 AM

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Opp/adj

sly marlin Mar 7, 2020, 11:07 AM

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okay, where's your triangle?

floral harbor Mar 7, 2020, 11:07 AM

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Its an arch

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Not a triangle

sly marlin Mar 7, 2020, 11:07 AM

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you need to use a right triangle to use trigonometric ratios

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(the simple opp/adj ones)

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you can't use a sector

floral harbor Mar 7, 2020, 11:08 AM

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Mhm.

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I could join the point with the y axis

sly marlin Mar 7, 2020, 11:08 AM

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okay, so what does that triangle give you for the coordinates?

floral harbor Mar 7, 2020, 11:09 AM

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Not sure

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I know the radius (hypotensue) is 2

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The angle is 3pi/10

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?

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Is x = 2/sin(3pi/10)

sly marlin Mar 7, 2020, 11:16 AM

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sin(3pi/10) < 1

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that means x>2

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does that make sense?

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@floral harbor

floral harbor Mar 7, 2020, 11:17 AM

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Yes.

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But it's bigger than hypotensue

silent plank Mar 7, 2020, 11:19 AM

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those are contradictory

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📎 unknown.png

floral harbor Mar 7, 2020, 11:20 AM

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Ah yes.

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So it doesn't make sense.

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Oof I'm confused.

silent plank Mar 7, 2020, 11:24 AM

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consider that triangle,
how would you find the length of the blue line?

floral harbor Mar 7, 2020, 11:24 AM

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sine of pi/5 would give me (blue line)/2

silent plank Mar 7, 2020, 11:24 AM

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yes

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contiune

floral harbor Mar 7, 2020, 11:25 AM

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Blue line/2sin(pi/5) = 1

silent plank Mar 7, 2020, 11:26 AM

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that's working against your goal, (also parentheses)

floral harbor Mar 7, 2020, 11:26 AM

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Ah it's true.

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Blue line = 2sin(pi/5)

silent plank Mar 7, 2020, 11:27 AM

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yes.

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and that will be the y-coordinate of that point

floral harbor Mar 7, 2020, 11:28 AM

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Mhm.

silent plank Mar 7, 2020, 11:28 AM

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(because the point is that many units above the x-axis)

floral harbor Mar 7, 2020, 11:28 AM

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Yes.

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Tan pi/5 = (2sin(pi/5))/red line

silent plank Mar 7, 2020, 11:29 AM

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what ratio does tan give you?

floral harbor Mar 7, 2020, 11:29 AM

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Opp/adj

silent plank Mar 7, 2020, 11:29 AM

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oh wait

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misread what you wrote

floral harbor Mar 7, 2020, 11:30 AM

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Ah OK.

silent plank Mar 7, 2020, 11:30 AM

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you could use that, or you could use a simpler trig ratio directly

floral harbor Mar 7, 2020, 11:30 AM

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Cos

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cos(pi/5)= Red line/2

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Red line = 2cos(pi/5)

silent plank Mar 7, 2020, 11:33 AM

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yeh

floral harbor Mar 7, 2020, 11:40 AM

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Ok.

whole zephyr Mar 7, 2020, 2:23 PM

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Hi! I have a question. For exercises that involves finding the others trigonometry functions having the value of one, if it's negative, do I have to include the negative in the identities? My teacher says no.

dark sparrow Mar 7, 2020, 2:23 PM

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what's "it"

whole zephyr Mar 7, 2020, 2:25 PM

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The result. For example Tanx = 1.

dark sparrow Mar 7, 2020, 2:40 PM

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oh like "here's the value of one trig function at x, find the values of the other five trig functions at the same x"?

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to determine the signs of those, you need to know what quadrant x is in

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for which extra information should be supplied

whole zephyr Mar 7, 2020, 2:53 PM

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Oh, so my teacher was write. Thank you!

dark sparrow Mar 7, 2020, 2:54 PM

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write 📝 is not the same as right ➡️

sacred lynx Mar 7, 2020, 5:41 PM

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Is heron formula is applicable to a point in space

tribal wind Mar 7, 2020, 5:47 PM

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n o

solid kiln Mar 7, 2020, 11:21 PM

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📎 unknown.png

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how do i do this?

tacit karma Mar 7, 2020, 11:44 PM

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@solid kiln You can start by realizing that the missing angles in that quadrilateral are congruent

solid kiln Mar 7, 2020, 11:46 PM

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@tacit karma i already solved it, thanks alot anyways:)

tacit karma Mar 7, 2020, 11:46 PM

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okay

rich wolf Mar 7, 2020, 11:47 PM

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@tacit karma cursed name

minor wren Mar 8, 2020, 12:19 AM

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How is number 8 solved? Maybe just a link to a video or something would help me

📎 image0.jpg

mystic dock Mar 8, 2020, 12:23 AM

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Not sure about what I am telling you since the number seem a bit weird but; whats the "primary" relation in a right triangle?
it starts with p ;p

minor wren Mar 8, 2020, 12:28 AM

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Uh, proportion?

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: /

mystic dock Mar 8, 2020, 12:31 AM

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Well I would say Pythagorean theorem but as I said the numbers seem suspicious, let me see if thats actually the way to solve it

minor wren Mar 8, 2020, 12:31 AM

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ok

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Thank you by the way

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I'm dumb

mystic dock Mar 8, 2020, 12:35 AM

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yeah it is definitely solvable with Pythagorean but the number you find is weird, just that

minor wren Mar 8, 2020, 12:38 AM

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yeah

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I got 7.549

rich wolf Mar 8, 2020, 12:41 AM

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What was the exact number

sleek tulip Mar 8, 2020, 1:11 AM

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Is this the right channel to ask about analytic geometry?

tribal wind Mar 8, 2020, 1:12 AM

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yea

sleek tulip Mar 8, 2020, 1:13 AM

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I have an assignment question that isn't quite in a form that I can related to my notes ect, I just want to make sure my approach isn't just completely flawed

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📎 unknown.png

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more asking if the logic I used to find n is valid than anything else

tribal wind Mar 8, 2020, 1:19 AM

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yea the logic is good

sleek tulip Mar 8, 2020, 1:19 AM

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thanks

olive plover Mar 8, 2020, 2:10 AM

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📎 20200307_180923.jpg

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would it be more efficient to solve that using 1+cot^2=csc^2 or unit circle

silent plank Mar 8, 2020, 2:22 AM

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about the same. try both
use w/e you're most comfortable with

rich wolf Mar 8, 2020, 2:44 AM

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what is cot theta by definition

olive plover Mar 8, 2020, 2:46 AM

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📎 20200307_184532.jpg

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idk what side is what of the triangele

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i know csc= 1/sin

rich wolf Mar 8, 2020, 2:47 AM

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,rotate

somber coyoteBOT Mar 8, 2020, 2:47 AM

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📎 251927217800478720.png

rich wolf Mar 8, 2020, 2:47 AM

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cos is horizontal

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sin is vertical

olive plover Mar 8, 2020, 2:48 AM

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hm

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where should i put the 3 and 2 in the triangle

rich wolf Mar 8, 2020, 2:48 AM

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think about it

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what is csc

olive plover Mar 8, 2020, 2:49 AM

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i thought and it was wrong

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1/sin

rich wolf Mar 8, 2020, 2:49 AM

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what is sin

olive plover Mar 8, 2020, 2:49 AM

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i know

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wait

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-3 in opposide and 2 hypothenus ? thats sin

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but i eneed 1/sin

rich wolf Mar 8, 2020, 2:51 AM

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dude work with me

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what is the definition of sin

olive plover Mar 8, 2020, 2:51 AM

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side opposite the angle that you are conducting the functions on over the hypotenus

rich wolf Mar 8, 2020, 2:52 AM

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so sine = opp/hyp

olive plover Mar 8, 2020, 2:52 AM

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yes

rich wolf Mar 8, 2020, 2:52 AM

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and csc = 1/sin

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so what is 1/(opp/hyp)

olive plover Mar 8, 2020, 2:53 AM

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hyp/opp

rich wolf Mar 8, 2020, 2:53 AM

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do you get it now

olive plover Mar 8, 2020, 2:54 AM

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i think i do but the teacher key got a different answer

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so im confused

rich wolf Mar 8, 2020, 2:54 AM

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well that's not the question you're trying to answer

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it says to find cot

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but you're given csc

olive plover Mar 8, 2020, 2:55 AM

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what i mean is i think the teacher marked the sides of the triangle wrong

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1 sec

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📎 JPEG_20200307_185635.jpg

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are the sides right

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atleasxt the two

rich wolf Mar 8, 2020, 2:57 AM

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yeah that's right

olive plover Mar 8, 2020, 2:57 AM

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oh i knew it

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tyhe teacher got it wrong

silent plank Mar 8, 2020, 2:57 AM

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what did the teacher do?

olive plover Mar 8, 2020, 3:00 AM

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📎 20200307_190003.jpg

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thisa

rich wolf Mar 8, 2020, 3:01 AM

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yeah that's wrong

silent plank Mar 8, 2020, 3:01 AM

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^

rich wolf Mar 8, 2020, 3:01 AM

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good job

olive plover Mar 8, 2020, 3:01 AM

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ty

rich wolf Mar 8, 2020, 3:02 AM

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now you can tell your teacher she's dum

olive plover Mar 8, 2020, 3:02 AM

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ye

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she has a some sort of memory loss so maybe thats why

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📎 20200307_191617.jpg

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did i do this correctly or the squareroot of 91 should had a negative infront? teacher key looks weird again

silent plank Mar 8, 2020, 3:19 AM

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-ve since its below the x-axis

olive plover Mar 8, 2020, 3:19 AM

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yes i thought sdo

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\

silent plank Mar 8, 2020, 3:20 AM

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does the question specifically mention quadrant 4?
what's the teacher saying?

olive plover Mar 8, 2020, 3:20 AM

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yees

merry scroll Mar 8, 2020, 4:18 AM

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hi! can anyone help me figure this problem out? you were supposed to apparently find the length of x using only these two values.

📎 20200305_172049.jpg

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ps im only in the 8th grade algebra 1 so I'm not very familiar with geometry or trig

silent plank Mar 8, 2020, 4:23 AM

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consider similar triangles

merry scroll Mar 8, 2020, 4:38 AM

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i have no idea what that means?

white cradle Mar 8, 2020, 4:39 AM

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oof

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so you aren't aware of geometry, trig or similar triangles

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let us begin with what you do know related to this question?

merry scroll Mar 8, 2020, 4:40 AM

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nothing at all, they just gave me this

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okay, after looking it up I kinda get it, but I don't know how it would help me

silent plank Mar 8, 2020, 4:46 AM

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which method does it show?
similar triangles or trig?

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show a pic of it if you can

merry scroll Mar 8, 2020, 4:48 AM

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I don't really know, this was during a test, so I couldn't take a pic of it, and the picture I provided is what the test showed me

silent plank Mar 8, 2020, 4:48 AM

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as in what you looked up

merry scroll Mar 8, 2020, 4:49 AM

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oh

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I just looked up what similar triangles meant

silent plank Mar 8, 2020, 4:52 AM

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not sure why'd they give you that without teaching that stuff yet

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what parts of geo do you actually know?

merry scroll Mar 8, 2020, 4:57 AM

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i know stuff about angles, cogruency and translations and stuff

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i think the test was just to see what we know

silent plank Mar 8, 2020, 4:57 AM

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congruency and similarity are relatively close

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📎 unknown.png

merry scroll Mar 8, 2020, 5:00 AM

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hm yeah I know that part, but how would I use that to solve for x?

silent plank Mar 8, 2020, 5:01 AM

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unlike congruent triangles, instead of corresponding sides being equal,
corresponding sides are in the same ratio

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triangles ABC and DBA are similar
BD corresponds to AB
AB corresponds to BC
which gets you
BD/AB = AB/BC
32/x = x/52

merry scroll Mar 8, 2020, 5:05 AM

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oh!

silent plank Mar 8, 2020, 5:07 AM

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alternatively you can use trig

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$\cos(B) = \frac{BD}{AB} = \frac{AB}{BC}$

somber coyoteBOT Mar 8, 2020, 5:08 AM

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ramonov:

📎 220517274845577216.png

silent plank Mar 8, 2020, 5:08 AM

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to reach the same result

merry scroll Mar 8, 2020, 5:09 AM

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oh that makes so much sense now!

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thank you so much!

alpine wadi Mar 8, 2020, 12:55 PM

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If A B C D are 4 points on a plane, of which neither 3 are colinear
A) how many lines are defined with thise points
B) how many triangles are defined by those points

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📎 JPEG_20200308_135623.jpg

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This is the solution for a

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But I have no clue how to solve it

white cradle Mar 8, 2020, 1:01 PM

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alright, no three points are collinear

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you know what that means?

alpine wadi Mar 8, 2020, 1:03 PM

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They arent in a straight line?

white cradle Mar 8, 2020, 1:05 PM

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yes indeed

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now what gives you, is a leverage to do a neat and simple observation

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in this case, that is, you can draw a unique line by choosing any 2 of the four points

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emphasis on unique, specifically since no three are collinear

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you get that?

dark sparrow Mar 8, 2020, 1:06 PM

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,rccw

somber coyoteBOT Mar 8, 2020, 1:06 PM

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Couldn't find an attached image in the last 10 messages

dark sparrow Mar 8, 2020, 1:06 PM

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rEEEEEEEEEEE

alpine wadi Mar 8, 2020, 1:07 PM

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Lol

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📎 JPEG_20200308_135623.jpg

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,rccw

somber coyoteBOT Mar 8, 2020, 1:08 PM

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📎 248065676214927360.png

alpine wadi Mar 8, 2020, 1:12 PM

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and @white cradle while I can draw it and figure it out like that, I want to know how to use the approach shown in the solution

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in the book

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it is the problem number 170.

white cradle Mar 8, 2020, 1:12 PM

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i didnt say draw it lol

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i only said, by choosing any 2 of the 4 points, you will be defining a unique line

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in which case, the number of lines you can draw would be the number of ways of choosing 2 points from 4 points

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aka 4 choose 2, aka 4C2

alpine wadi Mar 8, 2020, 1:14 PM

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oh, so that is what it means

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thanks

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and what about the next step

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_

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the 43 / 52

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where do the 3 and 5 come from

white cradle Mar 8, 2020, 1:15 PM

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you dont know what 4C2 means?

alpine wadi Mar 8, 2020, 1:15 PM

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now I do

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I think

white cradle Mar 8, 2020, 1:15 PM

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$^nC_r = \frac{n!}{r!(n-r)!}$

somber coyoteBOT Mar 8, 2020, 1:15 PM

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FlynnXD:

📎 216861413157765120.png

alpine wadi Mar 8, 2020, 1:15 PM

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it means from 4 points we choose 2

white cradle Mar 8, 2020, 1:15 PM

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nCr is a general expression of choosing r objects from n objects

alpine wadi Mar 8, 2020, 1:15 PM

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now I have no clue, again

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oh, ok

white cradle Mar 8, 2020, 1:16 PM

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you can figure out this expression if you think about it

alpine wadi Mar 8, 2020, 1:16 PM

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n is the number we choose from and r is the number of object we can chose

white cradle Mar 8, 2020, 1:16 PM

#

$n! = n(n-1)(n-2)...(2)(1)$

somber coyoteBOT Mar 8, 2020, 1:16 PM

#

FlynnXD:

📎 216861413157765120.png

white cradle Mar 8, 2020, 1:16 PM

#

thats called a

#

factorial

alpine wadi Mar 8, 2020, 1:17 PM

#

I have heard of those

white cradle Mar 8, 2020, 1:17 PM

#

so they just plugged in r=2 and n=4

alpine wadi Mar 8, 2020, 1:18 PM

#

but now I don't understand how we got 4-3 from that factorial

white cradle Mar 8, 2020, 1:19 PM

#

its 4*3

alpine wadi Mar 8, 2020, 1:19 PM

#

wont it be just 432*1

white cradle Mar 8, 2020, 1:19 PM

#

yes, but see denominator

#

its 2*1*2*1

alpine wadi Mar 8, 2020, 1:19 PM

#

so should I go 4*3 * 2 * 1

#

or just stop at 3

light socket Mar 8, 2020, 1:20 PM

#

can someone help me with a problem. I know the answer, but I don't get why my method doesn't work for solving it

white cradle Mar 8, 2020, 1:20 PM

#

(4x3x2x1)/(2x1)(2x1) = (4x3)/(2x1)

alpine wadi Mar 8, 2020, 1:20 PM

#

oh

white cradle Mar 8, 2020, 1:20 PM

#

must go till four, see i wrote all the expansions lol

#

just follow them

#

and simplify

alpine wadi Mar 8, 2020, 1:20 PM

#

ok, I get it now

white cradle Mar 8, 2020, 1:20 PM

#

kk

alpine wadi Mar 8, 2020, 1:20 PM

#

thanks

#

I'll try it that way

white cradle Mar 8, 2020, 1:20 PM

#

look up "n choose r" online

#

and see how that formula is derived

#

logically, its simple

alpine wadi Mar 8, 2020, 1:20 PM

#

do I do the same for triangles but 4C3 ?

white cradle Mar 8, 2020, 1:21 PM

#

ye

#

again only works cause no three points collinear

#

@light socket what is it

light socket Mar 8, 2020, 1:22 PM

#

📎 Screen_Shot_2020-03-08_at_6.52.17_PM.png

#

so angle T is 35 and angle A is 30 right?

#

so then if i draw a line connecting AT and another one connecting AB can I not use sin law to find AB, then use trig to find height of building

white cradle Mar 8, 2020, 1:24 PM

#

T and A are points, not angles

#

just for clarity, please mention the three vertices containing the angle,

#

as in angle ABC refering to the angle subtended at vertex B

light socket Mar 8, 2020, 1:25 PM

#

wdym, wouldn't T and A be angles if I draw lines AT and AB, creating angle of elevation and depressin

white cradle Mar 8, 2020, 1:26 PM

#

its just a wrong way of writing, either draw the angles explicitly and label them as T and A

#

or mention all three vertices

#

ill do it for u, what you mean by T is angle ATC and A is angle BAC where C is the base of the building

light socket Mar 8, 2020, 1:27 PM

#

ye

#

my bad

white cradle Mar 8, 2020, 1:27 PM

#

how would you use sin law, the angles dont belong to the same triangle even

#

drop out the laws and shit for a moment, and think bout it logically

light socket Mar 8, 2020, 1:28 PM

#

can't you do 1.6/sin 30 = x/sin 35

white cradle Mar 8, 2020, 1:28 PM

#

they dont belong to the same triangles

light socket Mar 8, 2020, 1:28 PM

#

Oh right

white cradle Mar 8, 2020, 1:29 PM

#

see, from triangle ABC, you can get x in terms of AC

#

using a simple trig ratio

#

and in triangle ATC, you can get a relation between TC and AC again

#

eliminate AC and youll find x

#

try it

light socket Mar 8, 2020, 1:29 PM

#

just to make sure, angle ABC is 60 then?

white cradle Mar 8, 2020, 1:29 PM

#

yes

light socket Mar 8, 2020, 1:31 PM

#

wdym by X in terms of AC

#

is x BC?

white cradle Mar 8, 2020, 1:31 PM

#

like x = (something) x AC

#

yes, x =BC, height of building which u want to find

light socket Mar 8, 2020, 1:33 PM

#

so i get

#

x/tan 30 = tan 35 (x+1.6) ?

white cradle Mar 8, 2020, 1:34 PM

#

yes

light socket Mar 8, 2020, 1:37 PM

#

so then I would do x/tan 30 = tan 35 (x) + tan 35 (1.6)

white cradle Mar 8, 2020, 1:37 PM

#

just plug in the values of the trig functions

#

and solve for x

#

not hard from here

light socket Mar 8, 2020, 1:41 PM

#

i think ive made a mistake

white cradle Mar 8, 2020, 1:42 PM

#

hm?

light socket Mar 8, 2020, 1:43 PM

#

cuz when i do that, i get 0.3x = 0.646

#

meaning the building is 2.15m tall, which is not the right answer

white cradle Mar 8, 2020, 1:43 PM

#

what is the ans

light socket Mar 8, 2020, 1:44 PM

#

7.52

#

it says that the equation should be h/tan 30 = (h+1.6)/tan 35

white cradle Mar 8, 2020, 1:45 PM

#

oh

#

that doesn't seem right

light socket Mar 8, 2020, 1:46 PM

#

📎 Screen_Shot_2020-03-08_at_7.16.09_PM.png

white cradle Mar 8, 2020, 1:46 PM

#

well theyre using angle of declination as angle of elevation

#

for whatever reason

light socket Mar 8, 2020, 1:47 PM

#

whats that

white cradle Mar 8, 2020, 1:47 PM

#

they flipped the angles

#

like instead of ATC being 35 they're taking TAC as 35

#

some error

light socket Mar 8, 2020, 1:47 PM

#

it doesn't make sense for tan 35 = H+1.6/x

white cradle Mar 8, 2020, 1:48 PM

#

ye they used the wrong angle that's all

#

dw, your work is correct, given the question you showed me

upper karma Mar 8, 2020, 2:14 PM

#

guys I need a proofing problem

#

oop

#

have*

#

for this question, it is given that they have an identical side and angle

📎 Screen_Shot_2020-03-08_at_9.15.10_PM.png

#

which leads me to believe I can say that CAE = CBD because Equilateral triangle

#

actually nvm

#

or could I say similar because of reflexive properties

alpine wadi Mar 8, 2020, 4:01 PM

#

how can I get good at geometry?

#

I hate it

#

especiallly the proofs

#

I am now stuck on this problem because I have no idea how to even approach it

#

Lines a and b are parallel and passing by line c. Point A belongs to a, B to b and C to c. How many planes is it possible to make from all the points and lines?

#

I have no idea how to even start doing this

upper karma Mar 8, 2020, 5:01 PM

#

I need some worksheets
Its to calculate angles and lengths of triangles using sin and cos and tan
And using the law of sins and cos
Hope im not bothering you all

dark sparrow Mar 8, 2020, 5:11 PM

#

i can attempt to throw one together

#

i need only one piece of information

#

how many problems?

#

@upper karma

#

if you don't answer, i'm gonna make you one with around 20

upper karma Mar 8, 2020, 5:29 PM

#

Hello

#

Im back

#

@dark sparrow

#

Ppease help

#

📎 JPEG_20200308_133124.jpg

#

📎 JPEG_20200308_133230.jpg

dark sparrow Mar 8, 2020, 5:33 PM

#

ok so wait

#

do you already have some problems and want me to help you with those

#

or do you want me to make you a worksheet with some problems

#

@upper karma

#

...

#

so.....

dire rampart Mar 8, 2020, 5:55 PM

#

pensive_ghost

upper karma Mar 8, 2020, 7:41 PM

#

i want you to give me a worksheet with the questions

meager spruce Mar 8, 2020, 7:52 PM

#

📎 image0.jpg

#

I need help with this one, I don't know where to start lol

devout harbor Mar 8, 2020, 8:17 PM

#

The sin graph will help if you know it's sketch at least?

meager spruce Mar 8, 2020, 8:19 PM

#

I understand the restriction is from 0 - pi, and I need to find the theta that makes it equal .25?

devout harbor Mar 8, 2020, 8:19 PM

#

You have to use the calculator, we can't do it by hand

meager spruce Mar 8, 2020, 8:19 PM

#

What would I input

devout harbor Mar 8, 2020, 8:20 PM

#

$\theta = \sin^{-1} (0.25)$

#

Use the sin inverse option

somber coyoteBOT Mar 8, 2020, 8:20 PM

#

Sup?:

📎 241927037135224833.png

devout harbor Mar 8, 2020, 8:20 PM

#

make sure the calc is in radian mode

meager spruce Mar 8, 2020, 8:20 PM

#

with rad or degrees

#

ok

#

I got .2526

devout harbor Mar 8, 2020, 8:22 PM

#

Okay, part a is easy, what do u think about part b

meager spruce Mar 8, 2020, 8:22 PM

#

wait so is the answer .2526

#

I'm confused

devout harbor Mar 8, 2020, 8:23 PM

#

Yes

#

Oh my bad

#

There is another answer

meager spruce Mar 8, 2020, 8:23 PM

#

is it + or -

devout harbor Mar 8, 2020, 8:23 PM

#

?

meager spruce Mar 8, 2020, 8:23 PM

#

What would the other answer be

#

or how would i get it rather

devout harbor Mar 8, 2020, 8:28 PM

#

Sorry

#

Yes the answer is +0.256 radians, for the second answer, it would be better if I show u the graph

#

so u know what's going on

meager spruce Mar 8, 2020, 8:29 PM

#

ok sounds good

devout harbor Mar 8, 2020, 8:29 PM

#

u know the graph right?

meager spruce Mar 8, 2020, 8:29 PM

#

The graph of sin?

devout harbor Mar 8, 2020, 8:30 PM

#

Yes

meager spruce Mar 8, 2020, 8:30 PM

#

yes I know that one

devout harbor Mar 8, 2020, 8:30 PM

#

Okay.

meager spruce Mar 8, 2020, 8:31 PM

#

sin(x) right?

devout harbor Mar 8, 2020, 8:31 PM

#

Yes.

meager spruce Mar 8, 2020, 8:31 PM

#

ok I got that

devout harbor Mar 8, 2020, 8:31 PM

#

📎 ysinx.png

#

We want to know where the value of sin(x) is 1/4

#

And it has two possible answers in the domain 0 < x < pi as you can see in the graph

meager spruce Mar 8, 2020, 8:32 PM

#

gotcha

#

so we have to find the other x value

devout harbor Mar 8, 2020, 8:32 PM

#

yes, can u think of how?

#

look at the x axis

#

You know the point of origin is (0,0) yes?

meager spruce Mar 8, 2020, 8:33 PM

#

yes

devout harbor Mar 8, 2020, 8:33 PM

#

Just think there's a 0 written there

#

so the gap b/w 0 and 0.2526 is..?

meager spruce Mar 8, 2020, 8:34 PM

#

double .25226

devout harbor Mar 8, 2020, 8:34 PM

#

?

#

No.

#

Just 0.2526

meager spruce Mar 8, 2020, 8:34 PM

#

would that be the answer

devout harbor Mar 8, 2020, 8:34 PM

#

No

meager spruce Mar 8, 2020, 8:34 PM

#

the distance from 0 to .25 is .25

devout harbor Mar 8, 2020, 8:34 PM

#

I'm talking about the gap, ie the difference b/w 0 and 0.2526

#

Yes.

#

Do you see where I have the "?" on the x axis?

meager spruce Mar 8, 2020, 8:34 PM

#

yes

#

190 - .25

#

*180 - .25

devout harbor Mar 8, 2020, 8:35 PM

#

Well the gap from the "?" to pi is the same as the gap from 0 to 0.2526

#

No, it's not 180 - 0.25

#

It's pi - 0.2526

meager spruce Mar 8, 2020, 8:35 PM

#

ok

devout harbor Mar 8, 2020, 8:35 PM

#

did u understand?

meager spruce Mar 8, 2020, 8:35 PM

#

Yes that makes sense

devout harbor Mar 8, 2020, 8:35 PM

#

Okay then

meager spruce Mar 8, 2020, 8:36 PM

#

Would I write pi - .2526

devout harbor Mar 8, 2020, 8:36 PM

#

Yes.

#

And you can see both answers are in the range of 0 < x < pi from the graph or by calculation

meager spruce Mar 8, 2020, 8:36 PM

#

yes

devout harbor Mar 8, 2020, 8:36 PM

#

okay

meager spruce Mar 8, 2020, 8:36 PM

#

so what about the all real numbers

devout harbor Mar 8, 2020, 8:43 PM

#

For that you need to know about the period of the sin function

#

@meager spruce

meager spruce Mar 8, 2020, 8:43 PM

#

which is how often it completes a full rotation

devout harbor Mar 8, 2020, 8:44 PM

#

Yes.

meager spruce Mar 8, 2020, 8:44 PM

#

So I need to know the period of sin(.25)?

devout harbor Mar 8, 2020, 8:44 PM

#

Just the period of $\sin(\theta)$

somber coyoteBOT Mar 8, 2020, 8:44 PM

#

Sup?:

📎 241927037135224833.png

devout harbor Mar 8, 2020, 8:45 PM

#

LOok at your question, it's written sin(theta) = 0.25

meager spruce Mar 8, 2020, 8:45 PM

#

2pi right

devout harbor Mar 8, 2020, 8:45 PM

#

So it's talking about y= sin(theta).

#

Yes.

meager spruce Mar 8, 2020, 8:46 PM

#

So I know the period of sin(x) is 2pi, and we need to find all the points that y = .25 within that?

devout harbor Mar 8, 2020, 8:47 PM

#

No.

#

For part (a), our restriction was that theta or x had to be between 0 and pi when sin(theta) or sin(x) = 0.25. For part b, there is no restriction.

#

That's all it's saying

meager spruce Mar 8, 2020, 8:47 PM

#

Wouldn't there be infinite answers then

devout harbor Mar 8, 2020, 8:48 PM

#

Yes and we need to write a formula for it

#

that's all

#

Btw do you have the numeric value for the 2nd answer?

#

it was pi - 0.2526, can u calculate that

meager spruce Mar 8, 2020, 8:49 PM

#

how do I simplify that

#

2.88

#

does that sound right?

devout harbor Mar 8, 2020, 8:49 PM

#

?

#

Yeah it's right

#

Simplify what?

#

Okay, now for part b, let's get down to business.

meager spruce Mar 8, 2020, 8:51 PM

#

I'm confused as to what to write for the formula

devout harbor Mar 8, 2020, 8:51 PM

#

I'll write it down and also explain

meager spruce Mar 8, 2020, 8:51 PM

#

ok thanks

devout harbor Mar 8, 2020, 8:51 PM

#

Or maybe you could write it after I'm done explaining

#

The period is 2pi, so we know for sure that the sin function will repeat it's value after 2pi radians. It could also repeat earlier, like sin(theta) is 1/4 at 0.2526 and also at 2.88. The difference is not 2pi. But these are the only two answers.

#

So we separate them both. For 0.2526, if we keep adding 2pi to it, then the sin function will have a value of 1/4

meager spruce Mar 8, 2020, 8:53 PM

#

makes sense

devout harbor Mar 8, 2020, 8:53 PM

#

And now you also keep addin 2pi to 2.88

meager spruce Mar 8, 2020, 8:54 PM

#

That makes sense

#

but what would the equation be

devout harbor Mar 8, 2020, 8:54 PM

#

📎 another_sin.png

#

You have to keep adding 2pi, that's the hint for the equation

#

We could add 2pi one time

#

Or 2 times

#

3 times, etc

meager spruce Mar 8, 2020, 8:55 PM

#

.2526 + 2pi(x) = .25

#

something like that?

devout harbor Mar 8, 2020, 8:56 PM

#

Forget the =0.25

meager spruce Mar 8, 2020, 8:56 PM

#

so just .2526 + pi(x)

devout harbor Mar 8, 2020, 8:56 PM

#

what's x?

#

🙂

meager spruce Mar 8, 2020, 8:57 PM

#

x is the number of times we add 2pi?

devout harbor Mar 8, 2020, 8:57 PM

#

Yes, and that's an integral value. We could add 0 times, 1 times, 2 times, etc..

#

Thing is, we could also subtract 2pi

#

Because we can go backwards

#

I suggest replacing x with n.

#

Where n is any integer.

#

So that's your solution

#

$0.2526 + n(2\pi) : n \in \mathbb {Z}$

meager spruce Mar 8, 2020, 8:58 PM

#

.2526 + 2pi(n) and 2.88 + 2pi(n)

somber coyoteBOT Mar 8, 2020, 8:58 PM

#

Sup?:

📎 241927037135224833.png

devout harbor Mar 8, 2020, 8:58 PM

#

Do the same for the other answer

#

Yes

#

So there you go.

#

$2.88 + n(2\pi) : n \in \mathbb {Z}$

somber coyoteBOT Mar 8, 2020, 8:58 PM

#

Sup?:

📎 241927037135224833.png

meager spruce Mar 8, 2020, 8:59 PM

#

what does Z stand for

devout harbor Mar 8, 2020, 8:59 PM

#

Integer.\

#

So I hope you understood.

#

Good bye

meager spruce Mar 8, 2020, 9:00 PM

#

Thanks for the help!

#

I understand now

devout harbor Mar 8, 2020, 9:00 PM

#

np

meager spruce Mar 8, 2020, 9:00 PM

#

good bye

digital gulch Mar 8, 2020, 10:22 PM

#

What’s a locus?

silent plank Mar 8, 2020, 10:24 PM

#

,w locus

somber coyoteBOT Mar 8, 2020, 10:24 PM

#

📎 wolf.png

Display results online and refine query

digital gulch Mar 8, 2020, 10:33 PM

#

Oh thanks

whole panther Mar 9, 2020, 9:01 AM

#

📎 IMG-dca500b9fff1f34703cc580954ed8194-V.jpg

#

how do i find the volume of that?

dark sparrow Mar 9, 2020, 9:07 AM

#

,rccw

somber coyoteBOT Mar 9, 2020, 9:07 AM

#

📎 183668144404037632.png

dark sparrow Mar 9, 2020, 9:07 AM

#

what is this shape

eternal crag Mar 9, 2020, 9:16 AM

#

~~physics textbook swim pool~~

whole panther Mar 9, 2020, 9:19 AM

#

both sides are rectangles

rotund galleon Mar 9, 2020, 9:20 AM

#

So it's just an oblong?

#

(idk the proper name.)

#

rectangular prism, thats the one

whole panther Mar 9, 2020, 9:20 AM

#

i think its a frustum but not sure

#

maybe

#

so what's the volume?

rotund galleon Mar 9, 2020, 9:21 AM

#

Well are the parrellel sides different length?

whole panther Mar 9, 2020, 9:21 AM

#

no

#

both 3.3 meters

rotund galleon Mar 9, 2020, 9:21 AM

#

Vol = b*w*h

whole panther Mar 9, 2020, 9:21 AM

#

what does that mean

#

w

rotund galleon Mar 9, 2020, 9:22 AM

#

width

#

It'll be easier if you google this yourself man

#

Just google: volume of a rectangular prism

whole panther Mar 9, 2020, 9:22 AM

#

im getting 10 different answers in google

#

idk why

#

and what's b?

rotund galleon Mar 9, 2020, 9:23 AM

#

base length

#

Trust me google it

silent plank Mar 9, 2020, 9:23 AM

#

its not a rectangular prism

rotund galleon Mar 9, 2020, 9:23 AM

#

he said that the parellel sides were same length

whole panther Mar 9, 2020, 9:23 AM

#

yes

#

its not rectangular

rotund galleon Mar 9, 2020, 9:24 AM

#

what, you said they were the same -_-

#

Okay. Well in that case take the average.

#

(of the two sides that are of different length)

#

and you can apply the rectangle formula. It is often best to get a geometric visualization for this, so a youtube video would really really help

whole panther Mar 9, 2020, 9:27 AM

#

2167.28?

silent plank Mar 9, 2020, 9:27 AM

#

maybe? i can't read your handwriting

whole panther Mar 9, 2020, 9:28 AM

#

base 1: 3.3 and 2.4

#

base 2: 3.3 and 4.7

#

length 185

silent plank Mar 9, 2020, 9:29 AM

#

wait you just said they were both squares?

whole panther Mar 9, 2020, 9:30 AM

#

rectangles

#

sorry

silent plank Mar 9, 2020, 9:32 AM

#

ahk that makes more sense

#

just a trapezoidal prism then

#

2167.275 sounds about right

valid dagger Mar 9, 2020, 12:43 PM

#

Uh math noob here might be a dumb question but is
Csc = -2 is in Quadrant 4 equivalent to Cot = -√3

#

or is it just √3?

weary drift Mar 9, 2020, 12:54 PM

#

@valid dagger just looking at x in [0,2pi), csc(x)=-2 with x being in quad 4 does imply x=11pi/6, making cot(x)=-sqrt(3)

valid dagger Mar 9, 2020, 12:58 PM

#

Oki thank youu

upper karma Mar 9, 2020, 3:44 PM

#

hi can someone explain small angle approximation to me

#

like i know sin x is approximately equal to x but how does sin 1rad=1rad???

hidden scaffold Mar 9, 2020, 4:37 PM

#

So I have these 2 circles with radiuses 2 and 3. Now I need to create formule for the line which passes through A and B where P is at (0, 0)

📎 JPEG_20200309_173548.jpg

mortal heart Mar 9, 2020, 4:37 PM

#

I have done it so many times and I still don’t get it right

#

Hello I need help finding h2

📎 image0.png

white cradle Mar 9, 2020, 4:38 PM

#

ok

hidden scaffold Mar 9, 2020, 4:39 PM

#

H2 = sin(35) * 20 I think

#

Degrees

white cradle Mar 9, 2020, 4:39 PM

#

y 12

hidden scaffold Mar 9, 2020, 4:39 PM

#

20*

white cradle Mar 9, 2020, 4:39 PM

#

ye

hidden scaffold Mar 9, 2020, 4:40 PM

#

Rounded is 11.47

sleek sequoia Mar 9, 2020, 5:34 PM

#

whats the point of sin cos tan

#

??

#

ping me

ebon minnow Mar 9, 2020, 6:20 PM

#

Hey hey

#

I've got a pyramid I know that's it's squared, <SAC is 45° and AD=DC=BC=BA=20

#

How do I get SO

#

📎 IMG_20200309_2019532.jpg

ebon minnow Mar 9, 2020, 6:40 PM

#

nvm, I worked it out, but don't really understand why

#

nvm I'm just dumb

ebon minnow Mar 9, 2020, 7:03 PM

#

I've encountered a different problem now

#

http://prntscr.com/rdv75w

Lightshot

Screenshot

Captured with Lightshot

#

How do I get anything from this rectangle?

languid ingot Mar 9, 2020, 7:04 PM

#

Get anything?

#

It's 30 60 90

ebon minnow Mar 9, 2020, 7:04 PM

#

I need to get the volume

#

Excuse me for my bad english

#

@coral sapphire Sorry for tagging, can you help?

coral sapphire Mar 9, 2020, 7:10 PM

#

What do you know about 30 60 90 triangles

ebon minnow Mar 9, 2020, 7:11 PM

#

?

coral sapphire Mar 9, 2020, 7:11 PM

#

What about AC

ebon minnow Mar 9, 2020, 7:11 PM

#

it's xroot of 3

coral sapphire Mar 9, 2020, 7:11 PM

#

Correct

ebon minnow Mar 9, 2020, 7:12 PM

#

use the pythagorean theorem

coral sapphire Mar 9, 2020, 7:12 PM

#

not necessarily

ebon minnow Mar 9, 2020, 7:15 PM

#

I'm lost

#

it's ~1.73 to 2

hidden scaffold Mar 9, 2020, 7:17 PM

#

So I have these 2 circles which touch each other with radiuses 2 and 3. Then there is a line which touches both of the circles in points A and B. Now, I want to create the line in form y = ax for the touching (tangent?) line through A and B. Point P is (0, 0)

📎 JPEG_20200309_201500.jpg

ebon minnow Mar 9, 2020, 7:20 PM

#

Type 3: You know the long leg (the side across from the 60-degree angle). Divide this side by the square root of 3 to find the short side. Double that figure to find the hypotenuse.

#

got it

#

so now what

#

How do I get AB or BC are the corners 90 degrees?

coral sapphire Mar 9, 2020, 7:29 PM

#

Yes the corners are 90 degrees

#

Angle ABC is 90

mortal heart Mar 9, 2020, 8:16 PM

#

Sorry to resend this again because it gives me 11.47 and that was marked wrong. (I’m trying to find h2)

📎 image0.png

#

See?

📎 image0.png

rich wolf Mar 9, 2020, 8:27 PM

#

@mortal heart 20sin35

ebon minnow Mar 9, 2020, 8:29 PM

#

📎 IMG_20200309_215746.png

#

@rich wolf Do you know the formula how to calculate the volume of CAMB?

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AB = 2 , M is a mid-point

rich wolf Mar 9, 2020, 8:31 PM

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What shape is that

ebon minnow Mar 9, 2020, 8:31 PM

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a cube

rich wolf Mar 9, 2020, 8:31 PM

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K

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But what shape is CAMB

ebon minnow Mar 9, 2020, 8:32 PM

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triangular prism I guess

rich wolf Mar 9, 2020, 8:32 PM

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No

mortal heart Mar 9, 2020, 8:58 PM

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Didn’t work again

📎 image0.png

hidden scaffold Mar 9, 2020, 8:59 PM

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11.47

mortal heart Mar 9, 2020, 9:00 PM

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Imma try again with that

hidden scaffold Mar 9, 2020, 9:00 PM

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I said 11.47 the first time you asked 😄

mortal heart Mar 9, 2020, 9:01 PM

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Yeah I know I had 11.46 so I guess I confuse it lol

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Sorry for that

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Anyways it doesn’t matter because they changed problems

hidden scaffold Mar 9, 2020, 9:05 PM

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Ohw

upper karma Mar 9, 2020, 10:26 PM

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I need help on numbers 11 and 14 please.

📎 image0.jpg

silent plank Mar 9, 2020, 10:49 PM

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mAngles:
JKM + MKL = JKL

upper karma Mar 9, 2020, 11:13 PM

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Hmm...

silent plank Mar 9, 2020, 11:13 PM

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wait whoops typpo

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fixed

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and you already know:
MKL and JKL

upper karma Mar 9, 2020, 11:20 PM

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Mhm

upper karma Mar 10, 2020, 7:42 PM

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Why is arccos(-root2/2) not -45? It says the answer is 135.

silk crown Mar 10, 2020, 7:44 PM

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what is cos(-45°)

upper karma Mar 10, 2020, 7:44 PM

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Wouldn’t it be -1/root2?

silk crown Mar 10, 2020, 7:45 PM

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why?

upper karma Mar 10, 2020, 7:45 PM

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Cuz cos of 45 is 1/root2 so if it’s negative 45 than just put a negative sign right?

silk crown Mar 10, 2020, 7:45 PM

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Not really

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Try drawing the graph is cos(x)

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See where the value is negative

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(goes below X axis)

upper karma Mar 10, 2020, 7:47 PM

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For the cos graph both 45 are .7

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Negative 45 and positive 45 are .4

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No .7

silk crown Mar 10, 2020, 7:47 PM

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Yes

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Because cosine is positive in the 4th quadrant

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cos(-x) = cos(x)

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So where will the graph first be negative?

upper karma Mar 10, 2020, 7:48 PM

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After the -90 and 90

silk crown Mar 10, 2020, 7:49 PM

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alright so now try to figure out what value of cos we should put so that it comes as negative 1/√2

upper karma Mar 10, 2020, 7:49 PM

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135 and -135

silk crown Mar 10, 2020, 7:49 PM

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and why

upper karma Mar 10, 2020, 7:50 PM

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You tell me

silk crown Mar 10, 2020, 7:51 PM

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ok so try to think about what cos(180°-x) would become

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go back to the graph

upper karma Mar 10, 2020, 7:52 PM

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-1?

silk crown Mar 10, 2020, 7:52 PM

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why?

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It can't be a constant value

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X is a variable

upper karma Mar 10, 2020, 7:52 PM

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Right

silk crown Mar 10, 2020, 7:54 PM

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So try doing this:

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from 180°, move the point x degrees on the x-axis and see where it ends up

upper karma Mar 10, 2020, 7:55 PM

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Wait what?

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I don’t understand

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Damn

silk crown Mar 10, 2020, 7:56 PM

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Ok nevermind with graphs then, think back to the unit circle

upper karma Mar 10, 2020, 7:57 PM

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Wait 180 degrees is (-1,0) so cos would be -1

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Cuz it’s (cos,sin)

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And -45 degrees would be 315 and that’s 7pi/4 and it’s positive root2/2

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And 135 is negative root2/2 or 3pi/4 because the cosine value for the second quadrant is negative

silk crown Mar 10, 2020, 7:58 PM

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thats what I was getting to but yeah

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CAST -> cosine, all, sine, tangent

upper karma Mar 10, 2020, 7:58 PM

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Oh okay sorry I got confused with the 180-x stuff

silk crown Mar 10, 2020, 7:59 PM

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sorry I confused you with it lol

upper karma Mar 10, 2020, 7:59 PM

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I literally had no clue what to do I was just staring at my graph lol

silk crown Mar 10, 2020, 7:59 PM

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It's just the intuition behind where the +ve/-ve thing in the quadrants comes from

upper karma Mar 10, 2020, 8:00 PM

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Oh okay

silk crown Mar 10, 2020, 8:00 PM

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If you want to try to check out the parts where it's positive and where it's negative

upper karma Mar 10, 2020, 8:00 PM

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Wait why do we do cos of 45 when doing cos of 135

silk crown Mar 10, 2020, 8:00 PM

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wdym?

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cos(135°) = cos(180° - 45°) = -cos(45°) is what you'll see

upper karma Mar 10, 2020, 8:01 PM

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It’s cos of 135 so when we try to figure it out we can look at the 45-45-90 triangle and use cos45 which is root2/2 and that 135 is in second quadrant which means x is negative which means it’s -root2/2

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But what’s the reason we use cos(45)?

silk crown Mar 10, 2020, 8:01 PM

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Not sure what you mean lol

upper karma Mar 10, 2020, 8:02 PM

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Wait

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Let me see how I can word this

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Wait what does this mean cos(135°) = cos(180° - 45°) = -cos(45°)

silk crown Mar 10, 2020, 8:03 PM

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Let me draw a diagram

upper karma Mar 10, 2020, 8:03 PM

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Okay

silk crown Mar 10, 2020, 8:04 PM

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📎 IMG_20200311_013426.jpg

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So you can see that 135° + 45° = 180° right?

upper karma Mar 10, 2020, 8:05 PM

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Yes

silk crown Mar 10, 2020, 8:05 PM

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now if we do cos(180° - 45°) think that we're starting from the negative x-axis and drawing the 45°

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It would end up in the 2nd quadrant, where cosine is negative

upper karma Mar 10, 2020, 8:06 PM

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Right

silk crown Mar 10, 2020, 8:06 PM

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And we also formed a triangle with angle 45° here so we get the cosine from it

upper karma Mar 10, 2020, 8:06 PM

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Yes

silk crown Mar 10, 2020, 8:06 PM

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I guess what's what you were asking on how cos(45°) shows up here?

upper karma Mar 10, 2020, 8:06 PM

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Yes

silk crown Mar 10, 2020, 8:07 PM

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And again the negative sign is there because the triangle is in the 2nd quadrant

upper karma Mar 10, 2020, 8:07 PM

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Yea

silk crown Mar 10, 2020, 8:08 PM

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Is your doubt cleared?

upper karma Mar 10, 2020, 8:08 PM

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Yea I think I understand for the most part imma finish off my homework and I’ll be back if I got any more questions

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Alright I’ll see u later

silk crown Mar 10, 2020, 8:08 PM

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Aight

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glhf

upper karma Mar 10, 2020, 8:08 PM

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Thx u too

cursive folio Mar 11, 2020, 9:38 AM

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oh sorry my bad

silent vigil Mar 12, 2020, 3:10 AM

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can someone help me with this ? I am not sure if i am doing it right.

📎 unknown.png

silent plank Mar 12, 2020, 3:34 AM

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$(a-b)^2 \neq a^2 - b^2$

somber coyoteBOT Mar 12, 2020, 3:34 AM

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ramonov:

📎 220517274845577216.png

silent vigil Mar 12, 2020, 3:34 AM

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ooohh thanks

limber anchor Mar 12, 2020, 4:20 AM

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I just had a quick question about Trig

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So I’m on a scientific calculator and I want to do SinX = 7/25

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Do I have to do SinX/1 equals 7/25 and then cross multiply to get X?

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Wait no that wouldn’t work

rich wolf Mar 12, 2020, 4:28 AM

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@limber anchor you have to use inverse sine

limber anchor Mar 12, 2020, 4:29 AM

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So Sin^-1(7/25)?

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Wait I think I got it hold on

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Yeah I got it now thank you

rich wolf Mar 12, 2020, 4:31 AM

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@limber anchor lmao

limber anchor Mar 12, 2020, 4:32 AM

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Wait so would it be .28?

rich wolf Mar 12, 2020, 4:32 AM

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Degrees or rad?

limber anchor Mar 12, 2020, 4:32 AM

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Degrees

rich wolf Mar 12, 2020, 4:33 AM

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@limber anchor make sure you're in the right mode

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It is .28 Radians

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But 16 deg

limber anchor Mar 12, 2020, 4:33 AM

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I swear I hit Degrees

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It’s even highlighted Im so confused

rich wolf Mar 12, 2020, 4:34 AM

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What calculator?

limber anchor Mar 12, 2020, 4:34 AM

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TI-84 Plus

rich wolf Mar 12, 2020, 4:34 AM

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Press mode

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Then select degree

limber anchor Mar 12, 2020, 4:34 AM

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That’s what I did

rich wolf Mar 12, 2020, 4:34 AM

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Uh huh

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Now does it say degree on the screen

limber anchor Mar 12, 2020, 4:35 AM

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I don’t think mine says that when I do something like that

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Okay so it’s 16.26 but I round down to 16?

rich wolf Mar 12, 2020, 4:36 AM

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Look at the top of the screen lol

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Idk what you need to round to

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That's up to you

limber anchor Mar 12, 2020, 4:37 AM

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I think I do because it says I need to go round to the nearest whole number

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I really hope I don’t fail this test

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So the ratios for a reference angle would just be like 7/25 right do I even have to solve anything?

junior hazel Mar 12, 2020, 10:59 AM

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📎 image0.png

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Whaaaa

dark sparrow Mar 12, 2020, 12:08 PM

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@junior hazel do you still need help with this

junior hazel Mar 12, 2020, 12:10 PM

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@dark sparrow yes

dark sparrow Mar 12, 2020, 12:10 PM

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okay what's giving you trouble

junior hazel Mar 12, 2020, 12:16 PM

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How do I order these angles @dark sparrow

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Sorry I was reading something

dark sparrow Mar 12, 2020, 12:17 PM

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what do you mean

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do you not know how to tell which of these angles are bigger and which ones are smaller?

junior hazel Mar 12, 2020, 12:18 PM

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Well A could be 50 or 29

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Or c could be 44 or 29

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Same with B

dark sparrow Mar 12, 2020, 12:18 PM

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ANGLES are not SIDES

junior hazel Mar 12, 2020, 12:18 PM

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So b is 44?

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Or is it 29

upper karma Mar 12, 2020, 12:54 PM

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@junior hazel you still need help?

dark sparrow Mar 12, 2020, 1:04 PM

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@junior hazel angle B is neither of these

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do you even know what an angle is

upper karma Mar 12, 2020, 1:05 PM

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@junior hazel i think i can help you out

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http://sketchtoy.com/69129928

An animated sketch

Draw sketches and share replays with friends!

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let me know if this helps

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i tried to make it intuitive for you

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by drawing it out

junior hazel Mar 12, 2020, 1:20 PM

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@upper karma @dark sparrow back

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Thanks poly

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Yes I know what an angle is

upper karma Mar 12, 2020, 1:28 PM

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@junior hazel does my video make intuitive sense to you

dark sparrow Mar 12, 2020, 1:32 PM

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so how come you keep confusing angles with sides

junior hazel Mar 12, 2020, 1:38 PM

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Yes

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Ehhh

daring solstice Mar 12, 2020, 5:03 PM

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Hey I have a math question, its from a quiz I took yesterday

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Okay so for this question, Can I just subtract the area of the hallway+kitchen and bathroom from the total area?

📎 image0.jpg

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also, for the hallway and kitchen could I just do 8x18 to find the area of the two?

drowsy walrus Mar 12, 2020, 6:45 PM

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for your first question, im confused as to what area you need to solve for

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but for the second one yes, if the diagram is drawn correctly

gaunt falcon Mar 12, 2020, 6:59 PM

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May I ask for advice/suggestion on solving this problem: https://math.stackexchange.com/q/3578871/721644 ?

Mathematics Stack Exchange

Circumcircle of a square and an arbitrary point inside it

Point $T$ is inside the square $ABCD$. Let $A_1,B_1,C_1,D_1$ the other intersection point of the lines $AT,BT,CT,DT$ respectively and the circumcircle of the square $ABCD$. Prove:
$$|A_1B_1|\cdot|

daring solstice Mar 12, 2020, 7:58 PM

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Basically I had to find the area of the two bedrooms and the living room to find the cost of something which is a diff problem

fringe dirge Mar 13, 2020, 2:11 AM

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!15m

south prism Mar 13, 2020, 2:47 PM

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what would be the easiest way of $finding M \epsilon AB so that AM=2MB, A(-1,1) and B(5,7)$

somber coyoteBOT Mar 13, 2020, 2:47 PM

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Vulpea:

📎 276829183823577088.png

quiet mason Mar 13, 2020, 2:51 PM

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have you heard of the section formula

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you have AM:MB=2:1

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now use the section formula

south prism Mar 13, 2020, 2:53 PM

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never heard of it, thanks

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@quiet mason i've found the formula but if the ratio is 2:1 ==> m=2 and n equals 1?

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for $M=(\frac{(mx_2+nx_1)}{(m+n)}, \frac{(my_2+ny_1)}{(m+n)})$

somber coyoteBOT Mar 13, 2020, 3:00 PM

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Vulpea:

📎 276829183823577088.png

quiet mason Mar 13, 2020, 3:04 PM

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yes

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@south prism

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you have all the information you need now

south prism Mar 13, 2020, 3:05 PM

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thanks

dark sparrow Mar 13, 2020, 3:18 PM

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\in, btw

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finding $M \in AB$ such that $AM = 2MB$

somber coyoteBOT Mar 13, 2020, 3:18 PM

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Ann:

📎 183668144404037632.png

violet dagger Mar 13, 2020, 7:35 PM

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📎 image0.jpg

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Easy grometry but hard for mee

south pewter Mar 14, 2020, 1:37 AM

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Hi, how do I do question 1? I don’t understand how you use the original equation of f(x) to solve

📎 image0.jpg

jade valley Mar 14, 2020, 1:40 AM

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f(x) is only drawn on the graph. technically there is no "original equation of f(x)"

south pewter Mar 14, 2020, 1:41 AM

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So then how do I use it?

umbral snow Mar 14, 2020, 1:41 AM

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What's the transformations on f?

jade valley Mar 14, 2020, 1:42 AM

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The domain of f(x) is the interval on the x axis containing it. You can see the graph goes from x=-6 to x=2, so the domain is [-6, 2].

south pewter Mar 14, 2020, 1:42 AM

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Well for the first one it is five units right

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Okay

jade valley Mar 14, 2020, 1:43 AM

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The range is the interval on the y-axis containing f(x), so from y = -2 to y = 2, or [-2, 2].

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Then you have to look at the transformations in (a), (b), and (c) and see how they affect the domain and range

south pewter Mar 14, 2020, 1:43 AM

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Alright

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But I don’t know how to use the original

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I know the domain and range of the original but I don’t know how that helps me

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Do I use the values from the graph of the original?

jade valley Mar 14, 2020, 1:45 AM

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Think about what 2f(x) looks like compared to f(x). 2f(x) is just two times f(x) at every point on the graph. So if you go look at the graph at x = 2, you can see that the y value, also known as f(2), is y = 2.

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So then if you were to look at 2f(x) at x = 2, you would see 2 times what you saw before. 2*2 = 4.

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So 2f(x) is the whole graph scaled by two on the y-axis

wintry elm Mar 14, 2020, 1:47 AM

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Could I get help with this? I'm in an introductory university geometry course and we have just covered Menaleus and Cevas Theorem

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📎 unknown.png

jade valley Mar 14, 2020, 1:47 AM

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Similarly, f(x-5) is the whole graph shifted to the right by five units.

south pewter Mar 14, 2020, 1:48 AM

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Ohh

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So the domain in the first one is -1, 7

jade valley Mar 14, 2020, 1:48 AM

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yes correct

south pewter Mar 14, 2020, 1:50 AM

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Oh thank you

jade valley Mar 14, 2020, 1:51 AM

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np

wintry elm Mar 14, 2020, 2:04 AM

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^^?

upper karma Mar 14, 2020, 6:07 AM

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@dark sparrow i tagged you (explaining just so hopefully you aren't annoyed) because i wanted to ask you in specific if you remember things like the proofs for obtuse angles for law of cosines/law of sines?

dark sparrow Mar 14, 2020, 6:09 AM

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uh

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does... there even need to be a special case for obtuse angles?

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wait yeah for law of sines

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idk, i didn't remember it off the top of my head but i just handwaved a diagram in my head so catshrug

upper karma Mar 14, 2020, 6:12 AM

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but could you prove it if you needed to?

dark sparrow Mar 14, 2020, 6:12 AM

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yes

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i could put the diagram on paper

upper karma Mar 14, 2020, 6:13 AM

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okay

dark sparrow Mar 14, 2020, 6:13 AM

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i'm in the metro rn so that's. not exactly feasible atm

upper karma Mar 14, 2020, 6:14 AM

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oh ok

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i can wait?

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if you can do it later i mean

dark sparrow Mar 14, 2020, 6:16 AM

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oh you're expecting me to actually do it?

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h

upper karma Mar 14, 2020, 6:17 AM

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sorry

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never mind then

upper karma Mar 14, 2020, 8:43 AM

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Is the proof not done geometrically in the complex plane?

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@upper karma no

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or at least we're not talking about the same proof then

upper karma Mar 14, 2020, 9:27 AM

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Huh how would you define those functions then thonk

upper karma Mar 14, 2020, 10:05 AM

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@upper karma define which functions?

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sin cos etc

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using the unit circle and similar triangles

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?

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How do you define that algebraicly?

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i am not sure what you mean

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you use similar triangles

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Nvm it

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okay

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@upper karma btw i think law of sines/cosines has been around way longer than the complex plane

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but i might be wrong

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Yes probably

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@upper karma by like 8 centuries lol

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Ok

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Though how is that relevant sully

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because the law of sines/cosines didn't come from thin air

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they proved it using similar triangles and unit circle

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same with other trig

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trig was a thing way before complex numbers

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Does that mean you can't prove it using complex numbers?

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is that what i said?

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No I am asking why it is relevant that these were discovered before complex numbers

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In modern literatur nobody uses triangles

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i was responding to

N/𝔄 : Huh how would you define those functions then

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they've been defined for a very long time

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without using complex numbers

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Yeah but geometrically with drawing pictures which I find is not a good proof

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no not geometrically

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you just draw a picture to illustrate it

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the actual proof is algebraic

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it is just way easier to follow with a picture

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Okay so how do you define it algebraicly then without a picture

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@upper karma https://en.wikipedia.org/wiki/Law_of_sines#Proof

Law of sines

In trigonometry, the law of sines, sine law, sine formula, or sine rule is an equation relating the lengths of the sides of a triangle (any shape) to the sines of its angles. According to the law,

        a
        
          sin...

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the wikipedia has the proof

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Okay so how do you define it algebraicly then without a picture

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there is no picture in those lines of text..?

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They refer to the picture with that text

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what picture

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there is no picture mate

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The thing you're telling me right now is that a and b and c in the equations are undefined if there is no picture they are referring to

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look man i'm not looking to argue with you

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if you don't understand that abc are the sides

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then idk what to tell you

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They are the sides they refer to in the picture

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Is this that hard?

#

you could describe the sides with this sentence

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A triangle labelled with the components of the law of sines. Capital A, B and C are the angles, and lower-case a, b, c are the sides opposite them. (a opposite A, etc.)

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no picture needed

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are you happy now or do you still want to keep being mad for some reason

#

Interesting that you think I'm mad. Anyways. That is still in reference to a picture. It does not mention how the circle is constructed or what exactly the sin and cos are in which context. No notion of a coordinate system. I'm just telling you that I find the proof using complex numbers more rigorous because there those things are all defined properly

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what circle

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Where you define sin and cos in..?

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To make the triangle..?

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can you link me the proof that you are talking about

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with complex numbers

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I don't have a link though it is quite easy to construct it using the construction of sin and cos with complex numbers

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i mean can you find one online

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it doesn't have to be yours

#

just the one that you're talking about so i know which one you are referring to

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I can't seem to find it

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unlucky i suppose

iron rain Mar 14, 2020, 2:23 PM

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A = (6, 0, 0), C = (0, 6, 0), TS = 8 and BP = (1/4)BT. How do I find the coordinates of point P? This is probably really easy but I’m just not seeing it.

📎 image0.png