#geometry-and-trigonometry

1 messages · Page 12 of 1

foggy parcel
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in other words the PQ' will be 10

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since teh angle being 45 the two sides in the right tringle are eqaul

gilded lion
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yep

smoky jetty
foggy parcel
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QQ' will be 7

smoky jetty
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no, PQ'

foggy parcel
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Oh my bad

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yea u r right

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I meant the RQ' and PQ' will be equal

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whatever it will be cos45 = PQ'/10 {PR = 10}

smoky jetty
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it's also a 45-45-90 case, so 7.01 *square root = hypotenuse = ~10

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then u can find the value of RQ' using Pythagorean theorem where RQ' = hypotenuse^2 - base^2

foggy parcel
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having the value of PQ' u can get the value of QQ' & RQ' ..and with these u can get the value of RQ

smoky jetty
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thus, leading us to using pythagorean theorem once more to finally find RQ, or the hypotenuse of te right triangle RQQ'

foggy parcel
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I hope u get it

smoky jetty
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that's actually a pretty cool way, balls stealer, i only realized that now

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but if ever u'd like the easier way @gilded lion, u can refer to this

foggy parcel
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Well we can do it in anyway..

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This is the fun part of math lol

smoky jetty
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indeed!

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another way i found to find PQ' is through the equation 10^2 = x^2 + x^2

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as PQ'=RQ'

gilded lion
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It did thank you!

amber quartz
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Please anyone tell this

opaque swan
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Does anyone get it?

amber quartz
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Idk the answer...of my problem

amber quartz
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Actually i did it guys

dusk coral
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hi.. guys?

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ok i have some formula

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Inverse trigonometric functions and finding the angle of a right rectangle (as long as with sine): θ = arcsin(a\b)

grand heron
# opaque swan

you only know the length of that diagonal line and nothing else?

dusk coral
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I will try to solve it in the chat

dusk coral
grand heron
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I'm confused

dusk coral
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ok

grand heron
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no, I don't get what you were trying to say

dusk coral
grand heron
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who are you talking to now=-=

dusk coral
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with myself so that I understand to myself that I said something reasonable, and not necessarily correct

dusk coral
grand heron
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?

dusk coral
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ok i'm just talking to you through a translator

grand heron
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ah, its confusing to talk to you, I do not have a mathematical problem only here to help

dusk coral
dusk coral
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θ = arcsin(a\b)

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a^2+b^2=h^2

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15^2+20^2=150^2=300

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θ = arcsin(15\20)

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θ = arcsin 0.75 \ n2

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0.75\3.14*2

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≈ 0.47

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θ ≈ 0.47

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I finished everything

brisk trail
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so how did they find 2x

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or get 2x

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for question #4

ebon echo
brisk trail
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@ebon echo

ebon echo
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the angle subtended by an arc at the centre is double the angle subtended by it at any point on the remaining part of the circle

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and arc EB (4x) is subtended by EDB here

brisk trail
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what do u mean

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by subtended

ebon echo
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see the arc of length 4x between E and B

brisk trail
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yes

ebon echo
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we say that, the arc is made or subtended by EDB

brisk trail
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so they divided 4x in half and got 2x?

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it seems too simple

ebon echo
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actually there is a theorem that if EAB subtends an arc of length say x, D being anywhere on the circle will subtend the same arc with angle EDB = x/2

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incase I am just confusing you more, check this out,

brisk trail
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ok thanks

rancid knoll
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Ez pz

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the question was quite easy essa

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is anyone a calculus student here

brisk trail
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thanks for letting me know...

rancid knoll
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are you calc student

brisk trail
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no im taking pre calc but my friend asked for geometry help

rancid knoll
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oh

brisk trail
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and i cant remember anything

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and got stuck on that question

rancid knoll
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you will just practice

ebon echo
opaque swan
grand heron
civic elbow
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HELP

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HELP ME

timber cargo
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With?

iron blade
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hey yall

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anyone willing to answer a question?

static magnet
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can someone please help me with this

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how do they get this

grand heron
thin locust
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(ABC) is for the circumcircle of ABC right?

limpid onyx
thin locust
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ah ok ty

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it was the thing which made the most sense but i wasnt 100% sure

limpid onyx
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Is there a name for the group of shapes with n foci? (like created with n pins and a string)

violet shadow
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For my working out here

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Is the line supposed to be going through the circle at two points or is it a tangent?

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Cause I don’t think this method works if it goes through two points? As the radius isn’t equal to the distance between the centre and the line then

crude cedar
crude cedar
violet shadow
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Ok

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For my diagram the line is a tangent then?

crude cedar
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If you are trying to draw the line where k=15/8 then yes it would be

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As in y=15x/8

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If you just drew a random line then no it would not be a tangent since it does cross the circle at two points (very close though)

violet shadow
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Ye ok then

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Ye I just saw the question mentioned two distinct points

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Are u taking further maths right now

crude cedar
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Yes

violet shadow
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What topic are you guys on

crude cedar
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I mean we are doing 4 different topics (4 teachers) rn: Linear transformations (with matrices), Trigonometry and modelling, Functions and graphs and distributions

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Although we jump all over the place

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Like we do the last chapter in the text book before the second

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Year 12 currently

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So a lot of the stuff I am doing rn is just normal maths year 13

violet shadow
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Ye that’s fair

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We just started matrices

crude cedar
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I see

violet shadow
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I’ve done most of the second year normal maths and further maths

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But I skipped over matrices with transformations first year

crude cedar
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Yeah they love skipping random things

violet shadow
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Wasnt something I could self teach myself for some reason

crude cedar
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Then going back later

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Shame

violet shadow
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Most of the maths I learn I can’t even apply to normal maths questions

crude cedar
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Further maths can be quite annoying

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5+5

violet shadow
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Our teacher is making us to discrete and no one wants to do it

violet shadow
# crude cedar 5+5

If u use complex analysis and calculate the mass of the sun I think it’s 55

crude cedar
violet shadow
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💀

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Damn never seen that thing

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Like some new sticker on discord or something

crude cedar
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Mortifying

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Sleep schedule is in the gutter

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Although that goes for all further maths students

violet shadow
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Not really

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Chemistry takes up more time

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And it’s like not difficult to pick up the further maths concepts

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I wanted to do a past AS paper for normal maths and use further maths for all the questions and this and a binominal expansion was the only question I could actually try to do so

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Cause u can use maclaurin series for binominal expansion

crude cedar
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I do Maths, Further maths, Physics and Computer science

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So I do not know the horrors of chemistry that I have been told about

crude cedar
sinful remnant
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So I got a big question about solving a triangle

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Say I need to solve this triangle. So the first obvious step is using the law of cosines to find the missing side. Afterwards, I would use law of sines to find the angles.

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So rounding up my numbers, I would get that a=11.1

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I have like three questions about finding the measure of the missing angles.

  1. Should I use law of sines to find the missing angles or the law of cosines?
  2. If I use the law of sines, say I want to find first angle B so that would be B=62.4°, but if I also consider the supplement I would have B=117.6°. And so I gather that there are two solutions. However, if I first find angle C, then I would get that C=79.6° and if I get the supplement I would get C=100.4°. So is it correct to say that there are four possible triangles?
  3. Should I use the law of cosines instead? Or should I valid the law of cosines for the four solutions I got and then discard the ones where the law of cosines does not hold?
nocturne remnant
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there is only 1 possible triangle; the reason that sine rule produces extra possibilities it because you are putting in two sides and a non-included angle (SSA), while for cosine rule you are putting in three sides (SSS)

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here SSS implies congruence; SSA does not

violet shadow
somber coyoteBOT
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ed1r0n

vivid seal
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i don't know where to start and what to do, please help me

smoky jetty
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Segment ED intersects the two sides of triangle ABC and is parallel to the side AB of triangle ABC, hence ABC and triangle EDC are similar, and the ratio of their corresponding sides and angles are in proportion

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basic proportionality theorem, or think of the triangle ABC as a version of triangle EDC scaled-up proportionally

crude cedar
# vivid seal

EDC = 180-4x (angles on straight line sum to 180)
2x + (180-4x) + 78 = 180 (angles in a triangle sun to 180)

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Then solve for x

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And then because the two triangles are similar the angle y = the angle 2x

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y=2x

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Solve for y

smoky jetty
crude cedar
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And I don’t see anything wrong with what I have done

smoky jetty
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i guess so.. but from the equation, then the triangles are isosceles

crude cedar
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True but that looks about right

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Very roughly

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Very very

smoky jetty
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seems like it

crude cedar
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I do see where you are coming from but I am going to say the diagram is very not to scale

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Since the maths we have done seems to be correct

smoky jetty
crude cedar
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Means that I understand why you would be skeptical about the value calculated for x

smoky jetty
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ahh ok

sinful remnant
floral shale
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All 3 of which is given

nocturne remnant
sinful remnant
nocturne remnant
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If you use the law of sines it is not immediately clear whether the desired angle is acute or obtuse

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You are given two sides and an included angle, so there is only one possible triangle (because SAS implies congruence))

sinful remnant
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Just to ask again about congruence. Which two triangles would be congruent? Or is there a second meaning for congruence?

thin locust
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need a hint (like where to look at)

keen lintel
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My hint would be to try to prove BHC and BXC are congruent

thin locust
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oh ok ty

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ill try it

thin locust
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but i wasnt sure if that is enough

keen lintel
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Oh you did it the wrong way, do you know reverse construction?

thin locust
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oh no

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wait ill look it up

keen lintel
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Wait actually you dont need it

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Dont worry

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Urm so BHC and BXC are congruent immediately by the fact that X is the reflection of H over BC

thin locust
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yea

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thats what i also thought

keen lintel
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Then you just need to prove angle BCX= angle BAX,

thin locust
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oh

keen lintel
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Which is obvious by angle chasing

thin locust
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ah oh

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oh

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yea

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damn

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i forgot about that rule

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ty

keen lintel
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ah dont forget that lol, cyclic quads are important especially if ur looking at egmo

thin locust
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trying to not forget it but im having a hard time remembering it

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i often do it wrong

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but ty

keen lintel
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Ah no problem

upper karma
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kinda need help

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sorry 😅

crude cedar
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The linear scale factor (for each line) is 9/8

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So the area scale factor is (9/8)^2

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=81/64

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So 81/64 x 320 should get you the answer for a)

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Then for b) 24 x 9/8

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Then for c)

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Get the volume scale factor: (9/8)^3

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729/512

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So 1536 x 729/512 should get you the answer

crude cedar
upper karma
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yeah thank you very much

crude cedar
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np

flint wagon
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Hi everybody, I think I found a proof for the area of a triangle without having to know the height of the triangle

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For a isosceles triangle:

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and for a equilateral triangle:

pliant roost
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heron's formula? :)

flint wagon
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no, bc u don't need s

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i think right?

pliant roost
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I just think heron's simpler

flint wagon
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oh ok

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but, what is s?

pliant roost
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semi perimeter

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(a + b + c) / 2

flint wagon
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oh

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sad life

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i thought i was genius

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Idk if it's simpler tho

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my formula is shorter right?

flint wagon
pliant roost
pliant roost
flint wagon
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haha

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but, why isn't this being taught in schools?

pliant roost
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idk

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not in the curriculum

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how had you derived your formula? @flint wagon

flint wagon
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I have a proof, but i just have to translate it

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Do u want to see it?

pliant roost
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I don't really need the proof, just the outline of it

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I can fill in the details

flint wagon
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oh well, it's based on two circles with the radius of the sides look:

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then u just use this formula for the two circles

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and then you get a solution for where the two circles come together

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then u get your coordinates

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thus the height

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then use h*b/2

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and then you have your area

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also, the height is this

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you get it?

pliant roost
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wait lemme read

flint wagon
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oh alright

pliant roost
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so you basically constructed a triangle, yeah

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kinda clever, but I'd just solve an equivalent system of eq. lol

flint wagon
pliant roost
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heron's formula. :)

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also height = sqrt((c - (a^2 + b^2 + c^2)/2b)(c + (a^2 + b^2 + c^2)/2b)), may make it look simpler

flint wagon
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yeah, i agree

pliant roost
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sqrt((cb - (a^2 + b^2 + c^2)/2)(cb + (a^2 + b^2 + c^2)/2))/2 = A

flint wagon
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oh also, from this formula, i found a formula for a quadrilateral

pliant roost
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any quadrilateral?

flint wagon
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yeah

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but d is a diagonal

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so you do need that

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and for a parallelogram

pliant roost
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well then that's kinda trivial for sure

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parallelogram = A_triangle * 2

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lol

flint wagon
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bro take a guess how old i am

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@pliant roost

pliant roost
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15

flint wagon
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correct how tf

pliant roost
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you usually study those in 9th grade in my country, and I've just extrapolated it, so 15

flint wagon
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i know, but im in 12th grade tho 😂

pliant roost
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also you're usually interested in that at 15 years old

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also my grade system is different

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not that different for sure, but still

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you jumped a few classes, didn't you?

flint wagon
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haha ye, 3 to be exact

pliant roost
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lmao

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interesting how you considered it something valuable. I also would for a second ngl, but it would just not make sense if there was no such formula alr

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@flint wagon you can look up a geometric proof of Heron's formula and Brahmagupta's formula respectively, as they exist. they are beautiful in their sort

flint wagon
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yes it's true, mathematics has been in existence for a while, so someone must've considered finding a formula for this, which indeed happened to heron

flint wagon
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ayo @pliant roost check this out

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this does't happen with my formula

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so maybe mine is kinda better?

pliant roost
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just computation may bring issues

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which is fair

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but your formula will happen to do the same :(

flint wagon
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oh, why?

pliant roost
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because that's how computation works

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I am not a numerical stability expert

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but the deviance grows, as one side tends to s, and other to 0

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so the value jumps around

flint wagon
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oh ok

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but, i'm wondering, what would happen if you'd equate the two formulas to each other (mine and heron's)

floral shale
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Your equation and heron's are similar

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Heron beat you

elder sorrel
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can someone show me how to startuhhhh

quick viper
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RT/PR = QS/PQ = QR/ST?

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I think

smoky jetty
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could u elaborate?

undone moat
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Which I can't find as an explicitly mentioned property in the question.

flint wagon
flint wagon
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but look how long his formula is compared to mine

pliant roost
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it's just easier to remember

flint wagon
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true

bright olive
# elder sorrel can someone show me how to start<:uhhhh:826921081490636851>

PT = PR + 2.4
PR = x
PT = x + 2.4

and if you are confused about the 3ST = 4QR
then lets say at 3 ST is 36 then 1 ST = 12 (it doesnt really matter what number it is as long as the ratio is the same, but i would suggest to use numbers that can be devided easily(you know or memorize))
if 3ST is 36 and 3ST=4QR then
QR = 36/4
QR = 9

Then you can

12/9 = x+2.4/ x to find the answer

pliant pumice
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Hello! Isosceles triangles have 2 congruent angles. I found a proof for it. Is it correct?

smoky jetty
smoky jetty
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coz if it were 36=9 then ig this isn't equal

pliant pumice
grave pond
pliant pumice
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Yeah, I saw it already. But Euclid's proof looks a bit too complicated. If the proof I sent is right, it's much easier to understand and memorize

grave pond
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Yeah, it's what both of the sources credit to Pappus.

smoky jetty
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There has been much speculation and debate as to why Euclid added the second conclusion to the theorem, given that it makes the proof more complicated.
the second conclusion sounded reasonable tho

grave pond
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Nobody disputes the second conclusion is true, as far as I understand.

smoky jetty
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were the auxiliary lines of the same distance from the base?

grave pond
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Yes.

crystal oasis
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Hi

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So there is this funny thing that is called "volume of partial cone/triangle" and well i want to learn it, but i do not know where to learn it.

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Do any of you have some sort of website for learning and doing exercises?

thin locust
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i only need to understand what (as L is on the angle bisector) means?

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i dont understand the sentence/wording

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i understand the rest

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but what is meant by "as L is on the angle bisector"

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is it just like: L is on the ray AI which is the angle bisector of angle BAC

grave pond
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Yes, plus the central angle theorem for the arcs BL and LC, which says that AL also bisects angle BAC.

thin locust
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is central angle theorem just inscribed angle theorem but the other way around?

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oh wait

grave pond
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Yes, that's another name for the same theorem.

silent snow
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Taco

weak flare
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I'm pretty sure 2 and 3 are wrong

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And then like all of the 2nd page is probably wrong

weak crypt
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am i on the right track for these two

keen dirge
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is it possible to rewrite the function y=xsin(x^2) + 1 in terms of y? (solving for x)

grave pond
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Not in general -- the function isn't even injective, and y=1 could lead to x=±sqrt(n·pi) for any natural n.

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Even restricted to small intervals where the function is injective, it looks too cursed to be likely to have an inverse with a nice closed formula.

snow crystal
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How to approach this?

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I have to evaluate the alpha angle

dark sparrow
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angles BCO, ACD, EAO can be calculated immediately

snow crystal
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How? I dont have that knowledge

dark sparrow
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triangle BCO is isosceles, triangle ACD is right.

snow crystal
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Ohhj right, because of the radius

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Also, how do you know that triangle ACD is right?

dark sparrow
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multiple ways to show that

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for example from the fact that triangles AOC and COD are both isosceles

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and so angle OAC + angle DOC make up exactly half the total of internal angles in triangle ACD

snow crystal
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But if the angle OBC is 32° and triangle BOC is isosceles, then the angle OCB is equal to 32°, triangle OCD is also isosceles so the angle OCD is 67°, 67 + 32 is 99°

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That's the ACD angle

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Which would mean that triangle ACD is not right

dark sparrow
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angle OCB + angle OCD is not angle ACD

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it's angle BCD

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which need not be right

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in fact it differs from the right angle ACD by none other than the very same alpha you seek

snow crystal
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Ok I see it now, thank you

silent plank
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ty

upper karma
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Is geometry hard

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I never actually studied geometry

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I skipped to trig

foggy parcel
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well to understnad trig well u need to have a basic knowledge of geometry

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Geometry isn't hard

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Tip: If u wanna master trig right now, the geometry of triangles is crucial

upper karma
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I think geometry can be pretty hard. I skipped to trig too, now in calculus and there’s a lot of problem solving that has geometry related stuff, it’s hard if you didn’t do geometry haha. Trig is easier imo but ofcourse you need very basic geometry understanding for trig.

sick hemlock
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Honestly geometry requires alot of critical thinking I guess?

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Like even just using all the concepts you've learned could be pretty hard

timber cargo
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The geometry that’s taught in schools require memorization. But on the SAT math section, that requires critical thinking

slender totem
dark sparrow
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that is a lot of problems.

timber cargo
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Those problems really test your memorization

pliant pumice
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Hello! As I know, every triangle can be divided into 2 right triangles. Should I prove this statement, or it is too obvious?

hollow fulcrum
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You can say something like "We draw an altitude to the side AB which divides the triangle into two right triangles"

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Nothing really to prove...

pliant pumice
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I thought it needs a proof because if you have an obtuse triangle you can draw an internal perpendicular not to every edge

pallid vine
#

Every triangle must have at least one angle which is either right angled, or obtuse. If it's obtuse, you should make the base of the triangle be the side opposite the obtuse angle, and then you can draw an altitude down, as you've shown above. For right-angled triangles, it's a special case where you can make two smaller similar triangles

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Hopefully that kind of makes sense in words

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Oh wait shoot take that back

pliant pumice
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Yeah, I understand. But how do I explain it? Is it an axiom or what?

pallid vine
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I wouldn't say it's an axiom, but definitely quite a common fact. If you wanted to prove it, you can probably continue to think about the properties of triangles, and their internal angles

pallid vine
pliant pumice
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If I am writing a proof, can I use this "fact" without proving it?

pallid vine
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Depends how rigorous you want to be in your proof. If it's a relatively rigorous proof, then probably start from scratch and prove the fact before using it.

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Although, I think most people just use the fact as a given, so you should be alright if you wanted to just use it

hollow fulcrum
hollow fulcrum
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You can construct the point the altitude will go to using the pythaogrean theorem which is a proper proof

pliant pumice
hollow fulcrum
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Yeah

pliant pumice
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I will try, thanks

hollow fulcrum
#

np

pliant pumice
hollow fulcrum
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now you need to show that it is positive

pliant pumice
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What exactly?

hollow fulcrum
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c1

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needs to be between 0 and c

pliant pumice
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And if it's not? Should I just try another edge?

hollow fulcrum
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yes

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it is guaranteed to work if the edge is longest side

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so use that hypothesis

pliant pumice
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Ok, it makes sense. Thank you

sick hemlock
timber cargo
sick hemlock
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Nope, but I have seen some papers. It's not really as prevalent here as it is in US

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Where I live it's mostly just olympiads or competitions

pliant pumice
trail lily
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If I solve a trig quiestion like 7tan30 how do I make it radical form, pls help

trail lily
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i know what 7tan(30) is as a decimal, how do you find radical

lyric sonnet
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I love trig and geo.

trail lily
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can you help?

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so to find 7tan30 you just put in a calc but the calc at school only gives decimal form, 4.04145188433

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how do i keep in simplified radical

lyric sonnet
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firstly tan 30 = $((1/2)/(√3)/2)$

somber coyoteBOT
#

Ishigami Senku

lyric sonnet
somber coyoteBOT
#

Ishigami Senku

lyric sonnet
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then multiply by 7 and you get $7/√3$

somber coyoteBOT
#

Ishigami Senku

trail lily
lyric sonnet
trail lily
#

what is surds

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what-

lyric sonnet
thin locust
#

when you guys have to solve a geometry problem which is like this, do you draw the figure on a paper or are you able to "see" the figure

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idk how to describe it

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but, do you just see how the stuff is going to look like?

silent plank
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draw, always draw

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regardless of whether you think you can imagine it

smoky jetty
sick hemlock
upper karma
#

If I knew theta (written in black), does that mean I know theta (written in red)?

sick hemlock
upper karma
#

?

celest osprey
#

pls name the points of the triangle so it would be easy to describe

upper karma
celest osprey
#

here

upper karma
celest osprey
#

if de and mc

#

are parallel

#

then theta will be equal

upper karma
#

they are parrellel, but obviously mc is longer. does that matter?

celest osprey
#

no it doesnt

upper karma
#

thank you so much

celest osprey
#

my pleasure

sick hemlock
#

In general, if 2 parallel lines are joined by another line, then the angle made by the line joining the parallel lines will be equal

#

I'll send a figure later

smoky jetty
#

yep, hence, <E & <C are corresponding angles

upper karma
# celest osprey my pleasure

Here is the actual full question and my working out. I can't see anything i did wrong but the numbers seem a bit off. Can you check?

fallow dock
edgy panther
#

can anyone help me solve these trigonometric ecuations?

sick hemlock
#

For most of those you should try taking a term to the right side

#

That should provide some clarity

#

for example write sin2x - sinx = 0 as sin2x = sinx

sick hemlock
#

The 2nd one is a bit of a tricky one.

#

When do sine and cosine have opposite signs?

edgy panther
sick hemlock
#

Yep, so your answers lie there

#

I'm not really sure how you'd go about showing your work

edgy panther
#

ahhh i think i kinda get it now

sick hemlock
#

You could also use the formulae for sin2x and sin3x if you want

#

Yeah you can do like 2 of those with complimentary angles, and the rest with the addition formulae

violet shadow
#

I’m not 100% sure on part b

#

But I got 7.67

#

I find the equation of the line passing through The centre that is partake to other line

#

Then I found the equation of the normal to that that goes through circle

#

And find where it intersected the circle

#

Then found the distance between that point and point where the line given crosses x axis but idk if this is right cause it seems very long winded

sick hemlock
#

@edgy panther Hey I found out how you could go about showing your work for the 2nd one

#

I didn't notice the sin(-x) and was confused the entire time

#

But you can write -cosx as sin(90+x)

#

@violet shadow Did you find the coordinates of the centre?

violet shadow
#

Ye that’s 5,4

sick hemlock
#

I guess you could go about finding the perpendicular distance between l and centre then

#

I don't really understand what you meant so you might have done this only

#

Lol

violet shadow
#

Ye but it wants shortest distance isnt that from the edge of the circle?

sick hemlock
#

First try the shortest distance from the centre, then subtract radius ig

#

It seems right for some reason

#

Shortest distance between the centre of the circle and the line is the perpendicular distance from the line

violet shadow
#

Idk if that’s what the question wants tho

#

But ye I think your right

#

Find perpendicular distance and then subtract the radius should work

sick hemlock
#

Yeah, I just can't find a good explanation for this

#

Maybe something to do with right triangles

#

I'll brb

#

I've got it I think

#

I'll send a clean ss

violet shadow
#

I got 5.497

#

Perpendicular distance is 19root 5 all over 5

#

Subtract 3 which is radius

sick hemlock
#

@violet shadow

#

I guess this counts as a proof?

#

Line n is a tangent to the circle at the point where perpendicular distance cuts the circle

#

And it's parallel to the line l due to angles

#

So the distance between the parallel lines is the same throughout

#

And n only touches the circle at one point so that means that's the minimum distance

violet shadow
#

Well u have to find that line then

#

U have to find the tangent to the circle your way then

#

Which is long

sick hemlock
#

Yeah I wasn't suggesting a solution

#

I was suggesting a proof to that thing I said

sick hemlock
violet shadow
#

U got it aswell?

#

Ye I think my 7 was wrong cause I did it a long wounded way

#

I think this is correct tho

sick hemlock
#

Yeah

#

Well we learned something new today

violet shadow
#

The one time I didn’t use further maths I got it wrong

#

Ye

sick hemlock
#

Something about shortest distance from a circle

violet shadow
#

I usually use further maths for geometry

#

Cause there is a formula for perpendicular distance between a point and a line

sick hemlock
#

Honestly geometry is scary sometimes

#

You don't know if the question wants you to do it a long winded way

#

Like say, finding the orthocentre of a normal triangle

sick hemlock
#

Yeah I vaguely recall something similar

violet shadow
#

It’s in the vectors section

#

Trying to send a pic but it’s slow

sick hemlock
#

I saw a formula for perp distance from the origin nvm

violet shadow
#

K

edgy panther
sick hemlock
#

eyy found the formula for perp distance from a line

#

I hate it

solemn ivy
#

Can someone help

sick hemlock
upper karma
sick hemlock
#

Honestly, you didn't need to calculate tan inverse of 10 either

upper karma
ruby oak
#

I have no clue how to do this and need a walk through

crimson pawn
#

ask a help room

exotic yarrow
upper karma
meager mango
#

I’m so dumb

sick hemlock
#

But since you found the 2 angles to be equal, you could have simply set tantheta = tanalpha. And since the question is just asking for the diameter you don't need to calculate the angles @upper karma

upper karma
#

help

sick hemlock
#

help with...?

upper karma
#

this center

#

so confusing

sick hemlock
#

Okay, what would you need to write an equation for the circle

upper karma
#

coordinates

#

ig

sick hemlock
#

Just to clarify, equation of the circle means equation for points lying on the circle

upper karma
#

these were easy to find

#

idk bout that first pic tho

sick hemlock
#

So you found coordinates of 3 points lying on the circle I assume?

#

Nvm

upper karma
#

for this no

#

nvm

#

I meant

#

for this no

sick hemlock
#

okay, what's a speciality of circles that you can use to your advantage?

upper karma
#

they form diameter?

sick hemlock
#

or, each point lying on the circle is equidistant from the centre

upper karma
#

radius

sick hemlock
#

Though I guess you don't even need that

#

The question isn't asking for the equation of circle

upper karma
#

it is

sick hemlock
#

It's just asking you to find the diameter

upper karma
#

no?

#

it says equation

sick hemlock
#

But that's not what an equation of circle is, atleast where I've read

#

That's mostly just asking you to apply distance formula

upper karma
#

wait for this??

sick hemlock
#

by finding 2 points of a diameter

upper karma
#

I thought distance formula was for this

#

I'm soo confused

sick hemlock
#

Distance formula is for finding the distance between 2 points

#

Could be used wherever convenient

sick hemlock
upper karma
#

for my question, we just finding the center

upper karma
#

we got the points from the graph itself

sick hemlock
#

You found the radius of the circle

upper karma
#

cuz I just counted the boxes

sick hemlock
#

Alright, sorry I was confused by the wording of the question

upper karma
#

it's alr

sick hemlock
#

Been a while since I touched coordinate geometry

#

So yeah, these questions require you to locate the centre

#

Find the distance between the centre and a single point lying on the circle

#

and then apply distance formula for all x,y that are the same distance from the centre

upper karma
#

-3,4

#

BUT SHE SAID WE AINT GOTTA USE ANY FORMULA FOR THE QUESTIONS THAT HAVE GRAPHS ON

sick hemlock
#

the question is literally asking you to use a formula

#

You can't really not use a formula there

upper karma
#

wait this is confusing

#

imma brb.. I'll call my teacher hol up

sick hemlock
#

Let me confirm: You did this by calculating the radius, and then applying distance formula for all x and y that are the same distance away from the centre right?

#

Just do what you've already done

viral cave
#

hello

#

i want to have a discussion about 4th spacial dimension

#

this word "space" is important here

#

because time is also known as 4th dimension but I am talking about space specifically

#

does anyone have an example of a 4th dimensional object or thing which exists in real life?

#

which can be observed?

#

or measured.

#

Don't tell time.

upper karma
#

tysm anyways!

obtuse patio
#

we live in a 3d world

viral cave
#

but does that imply we can't observe or measure it?

obtuse patio
#

we cant even imagine it

viral cave
#

well

#

a circle can cut a line

#

so a point in line can see those atmost two points of the circle

#

a sphere can cut a plane

#

so a 2D being can see those curves

#

similarly

obtuse patio
#

yes

#

but we cant see the 4d

#

we can see the cut/shadow

viral cave
#

why can't something 4D come in contact in our space?

obtuse patio
#

it could

#

we cant prove it though

viral cave
obtuse patio
#

it would be a 3d shadow

viral cave
#

u have any example please?

obtuse patio
#

yeah one sec

viral cave
obtuse patio
viral cave
#

no

#

i said real life example

#

but thanks for this teseract image

obtuse patio
#

theres no real life example wym

#

4d is theoretical

viral cave
#

and thats what all I asked for

#

an s or no question

obtuse patio
#

i said that though alreayd

#

w/e

viral cave
#

and then, what if 4D doesn't exist at all?

obtuse patio
#

it may not

viral cave
#

i feels crazy

#

i know

#

i seem crazy

obtuse patio
#

if 4d exists maybe 5d exists too

#

who knows

viral cave
#

but what if the nature of space itself is like that

#

such that space can only have 3 dimensions

obtuse patio
#

maybe

#

we cant say

viral cave
#

i hope a mathematical proof or disprove in the future

obtuse patio
#

how

#

we cant

viral cave
#

why

obtuse patio
#

anything we do is 3d

#

how can you prove for example parallel unvierses exist

viral cave
obtuse patio
#

its the same idea to me

#

its so far out

viral cave
obtuse patio
#

thats not a proof

viral cave
#

so

obtuse patio
#

so what

viral cave
obtuse patio
#

if we can somehow find it existing yeah

#

but Im saying you cant prove it with like math

viral cave
#

hm....

obtuse patio
#

itd have to be shown through experiment or smth

#

maybe using dark matter

#

who knows

#

many people are actively working on these kind of questions

#

maybe you will too one day

viral cave
#

saying "we can't" is just as arrogant as saying "we can" I guess

#

it is just left there

#

thats why I said hope

obtuse patio
#

it may not be a good thing

#

if we find out it exists

viral cave
#

oh

#

why so

obtuse patio
#

we could mean nothing

viral cave
#

well we already are

obtuse patio
#

eh

#

i think it would make it worse

upper karma
sick hemlock
#

Allow me to explain properly

#

So, when you look at the 2 right triangles, they're similar

#

That also leads to the same conclusion that the sides are proportional

#

Similarly, since the angles are equal, the tan of those angles should also be equal. Therefore tantheta = tanalpha, which leads to ratio of the height from the ground to the radius of the cone formed is 10.

#

Even then, this question does not even require trigonometry, it's basic similarity

#

All I said is that if the angles are equal, then the tangent of those angles should also be equal

#

And that leads to the same conclusion you'd get by going the similarity route

#

@upper karma

upper karma
sick hemlock
#

Alright let me name the vertices one second

#

So, we're considering the triangles ADE and ABC here

#

Angle A is common to both the triangles, theta and alpha are equal, and Angle D and B are right angles

#

So all 3 angles are equal

#

A=A
D=B
E=C

#

So triangle ADE~triangle ABC

#

Now according to CPST, AD/AB = DE/BC = AE/AC

#

Using this, we can say that AD/AB = DE/BC

#

which gives you the same equation as above

upper karma
sick hemlock
#

Corresponding Parts of Similar Triangles

#

Similar figures are figures which are basically the exact same shape as each other, but differing in size

#

It's basically congruency but without the figures being the same size as one another

#

The sides of similar triangles are proportional to each other and the angles of vertices are the same (hence the same shape)

#

In determining similar polygons you need to see if the angles are the same

#

Hopefully that provides some context

smoky jetty
#

A yardstick casts a shadow of 24in. at the same time an electric post cast a shadow of 20ft. 8 in. In inches, what is the height of the electric post? Let h be the height of the electric post
I had this problem recently and Im somewhat skeptical of the triangles being similar. Because the statement did not say anything regarding the angles in the triangle being congruent to one another or state that the triangles are similar. But, if you put the given measures in proportion, you'd find h. But idk how I could make the statement stating that both are similar unless I assume that the interior angles are equal or, they're both right triangles.

sick hemlock
#

What's a yardsticksully

#

Okay

obtuse patio
#

Imperial

sick hemlock
#

@smoky jetty have you drawn a figure?

upper karma
#

lol

sick hemlock
#

Just calculate in inches lol

#

Another similarity question

upper karma
#

I know duh.. just being smartass

sick hemlock
#

1ft=12in isn't it?

smoky jetty
sick hemlock
#

You have to

smoky jetty
#

i have the answer, only if they are similar, but idk how I could prove that they are similar in a statement

sick hemlock
#

Otherwise it's not really solvable I don't think

smoky jetty
#

indeed

sick hemlock
#

Okay, so it's a yardstick and an electric pole

smoky jetty
#

otherwise, im having a geo concept gap, lol

upper karma
smoky jetty
sick hemlock
#

Whenever you are given pole like objects

smoky jetty
#

what are your thought?

sick hemlock
#

You kinda have to assume they're perpendicular to the ground

smoky jetty
#

yeah i thought so as well

sick hemlock
#

Unless stated otherwise

upper karma
#

right angles baby

sick hemlock
#

Yep

upper karma
#

we love that shit

smoky jetty
#

but i considered other factors being that one may be inclined as the other is perpendicular to the base

#

coz the problem didn't state such

sick hemlock
#

So I doubt the question wants us to consider those possibilities

smoky jetty
#

i see

sick hemlock
#

So for now, rest easy and whenever you're given poles or similar objects, just assume they're at right angles

smoky jetty
#

i kinda feel bad that i have to assume their angles just to prove they're similar, lol

sick hemlock
#

Yeah I know what you mean

#

You could also think practically, why would someone build an inclined electric pole?

smoky jetty
#

do u think assuming it would prove their similarity otherwise?

smoky jetty
sick hemlock
#

Yeah but only sadists build those

smoky jetty
#

lol i see

sick hemlock
#

Apparently engineers are infamous in the math community

#

Why would they make stuff hard on themselves by making poles on slight inclinations

smoky jetty
#

well ig in short, to solve the given problem, one must assume they're perpendicular or have the same interior angles?

sick hemlock
#

Assume they're perpendicular for now

#

In later classes that might change, I don't really know

smoky jetty
#

alright, thank u very much.

sick hemlock
#

Eh I didn't really help

smoky jetty
#

how come? lol

sick hemlock
#

I just acted like those teachers who say "That's just the way it is"

smoky jetty
#

ig my teacher gave that problem with that attitude, lol

sick hemlock
#

Yeah, though it makes life easier for us as well

#

Similarity won't work always

#

Sometimes you'll have to use trigonometry

#

And in those cases the poles being perpendicular helps a lot

smoky jetty
#

yeah

#

what grade are u in btw?

#

hs before senior higschool?

#

ig im 9th grade relative to yours

sick hemlock
#

Damn, similarity in 9th grade

smoky jetty
#

idk if we'll ever reach congruency&heron's, prob due to the curriculum

#

btw thx for the responses earlier, I thought I was the only one who had to assume the triangles were similar to solve it, or who knows

sick hemlock
#

No you do need to assume them to be perpendicular

#

You know why the triangles are similar right

#

The sun will cast a shadow at the same angle for any perpendicular distance at a given time

#

Since angle of elevation of the Sun does not change from the ground

celest osprey
smoky jetty
#

yeah I thought so as well

#

does that need to be explicitly said in the problem?

#

otherwise it's just assuming both are perpendicular to the ground?

celest osprey
#

wait i messed up

near harness
#

You can also use trigonometry to solve this problem.
Either way proving the non-perpendicular pair of angles is necessary.

sick hemlock
#

That wasn't his question though

#

He wanted to know why we had to assume the electric pole and yardstick to be perpendicular to the ground

smoky jetty
near harness
near harness
#

Where x is height.

#

Or in your case it is "h"

smoky jetty
jagged galleon
#

Does this shape have a name, and if so what is it called?
Just a cube with a cylinder cut out from all axes.

smoky jetty
#

ah yea, then you'd get x then

#

would u say that the problem should've explicitly said that the post and stick were perpendicular?

near harness
sick hemlock
uncut panther
#

Given the vector of coordinates v=(-3/4,k) it is requested that for k=1, express v as a linear combination of a=(2,3) and b=(5,-1)

I managed to resolve it but I don't know if it's right or if I misunderstanded the exersice

#

I thought v=(-3/4,k) was w and did w=x(2,3)+y(5,-1)

obtuse patio
#

v = Ca + Db

#

-3/4 = C*2 + D*5

#

And then the y component

#

Two unknowns two equations

#

Solve

uncut panther
obtuse patio
#

Plug the values back in and check

prime umbra
#

can someone please help with this 😭?

timber cargo
somber coyoteBOT
#

Daniel S.

timber cargo
#

n being your total number of sides

#

and the result being the summation of all angles

prime umbra
#
  • 2 and then * 180 to get the degree / sum
#

?

#

Thanks

timber cargo
#

You’re given that the polygon has a total of (x-8) sides, that’s your n value right there

#

So substitute that for n

#

and you’ll get what

#

@prime umbra Come back, don’t ghost me

obtuse patio
#

I think they already got it

timber cargo
#

I hope so

prime umbra
#

sorry 😭

#

what’d you say?

timber cargo
prime umbra
#

if it’s x-8

#

is my x what i get after 4320/180

stray spruce
#

pls help

still pelican
#

yo

#

nvm

obtuse patio
near harness
lost sky
short wyvern
#

$/sqrt(x2 - x1)^2 + (y2 - y1)^2$

#

but what do they mean by "the line"

#

?

#

$/sqrt{(x2 - x1)^2 + (y2 - y1)^2}$

somber coyoteBOT
#

Sanaltsalt

floral zealot
#

@short wyvern

short wyvern
#

yessir

floral zealot
#

backslash not forward

short wyvern
#

oof

floral zealot
#

\sqrt not /sqrt

short wyvern
#

alr

#

thanks again

floral zealot
#

good luck

short wyvern
#

alr

#

$\sqrt{(x2 - x1)^2 + (y2 - y1)^2}$

somber coyoteBOT
#

Sanaltsalt

short wyvern
#

but this is maths

#

just fill in y with "the line" and you should be fine

#

@stray spruce

lyric star
zenith forge
#

first multiply out the areas of both rectangles

austere blade
timber cargo
obtuse patio
snow crystal
#

"What's the sum of all the six angles marked on the picture", how to approach this?

violet shadow
#

Is there a way to do this question part C without the discriminant because it’s very long that way

trail lily
#

Somone draw this out

#

PLS

desert anvil
#

hello, can someone help me with this? just the solution would be fine.

celest osprey
#

4x-8=23

#

opposite sides are equal

#

in a parallelogram

#

and 47+2y-3=180

#

adjacent sides are supplementary in a parallelogram

waxen scaffold
#

A water park has hired Sharnee to build part of a ramp for a new water slide. She builds a 12-metre-long
ramp that rises to a height of 250 cm. To meet safety regulations, the ramp can only have a gradient between
0.1 and 0.25. Show that the ramp Sharnee has built is within the regulations.

can anyone show me how to do this i cannot understand

dark sparrow
#

do you know what gradient means?

#

in this context it is also commonly known as slope, though it depends on where you are from.

waxen scaffold
dark sparrow
#

how would you find the gradient of a line on a coordinate grid?

dark sparrow
#

missing parentheses...

waxen scaffold
dark sparrow
#

brackets

#

anyway

#

the phrase "rise over run" should have been said at least once in your class

waxen scaffold
#

yeah

dark sparrow
#

She builds a 12 m long ramp that rises to a height of 250 cm.

#

what are the rise and run here?

waxen scaffold
#

ohh i get it now

#

i didnt consider that

#

thanks

short wyvern
#

oh sorry

#

it's already answered

smoky jetty
lost sky
smoky jetty
# smoky jetty give it a try

I made a very rough illustration regarding the problem if u need to solve it asap, hopefully u know the nexts to do

dark sparrow
smoky jetty
#

the problem didn't specify if it's right triangle, i hope it represented the measures correctly

lost sky
lost sky
smoky jetty
#

yeah, but the problem didn't state it sohmmCat

keen fiber
#

someone solve this: sinx+siny=a and cosx+cosy=a, what is sinx+cosx interms of a

violet raft
smoky jetty
# trail lily

i mean it's pretty hard to assume that it's a right triangle here

lavish portal
#

Help this question, find alpha in terms of a, b, c, d
Given this is a rectangle where the intersection between four lines is randomly picked

fossil lava
#

Guys can anyone explain why the unit circle is centered at (0,0)

sick hemlock
#

to make life easier

dark sparrow
cedar grotto
#

You helped lots thank you for the explanation

austere blade
#

..?

#

I already finished that whole assignment

#

Yesterday TCC_Kek

#

10th

#

I’m not the best at math

violet raft
upper karma
#

yut

#

yur

#

can someone help me

#

<@&286206848099549185>

granite void
#

isnt AOB 80 too?

#

since O is the center

#

and since its a circle you know 2 sides of the triangle are = so know more about the triangle

#

then ACB is just the whole circle missing a part, which you know

rapid wraith
#

<@&286206848099549185> can anybody help with this question?

i need to find the probability of p(A|B) in order to see if probabilty of a and probability of B are independent or not. im looking to see of P(A)(B) is equal to P(A|B)

p(A)= 11/50
p(B) = 5/11

granite void
#

are you given more info?

rapid wraith
#

yes

granite void
#

might be handy

rapid wraith
#

the meaning of p(A) is the probability of picking cheerios

#

11/50 chance

#

p(B) is drinking the milk after eating the Cheerios

#

5/11 chance

#

just trying to see if they are independent

mint kite
#

multiply it

granite void
#

is p(B) the chance of drinking milk after eating cheerios or the chance of drinking milk after eating cereal?

rapid wraith
#

Its the probability of drinking the milk thats left in the bowl after eating cheerios

granite void
#

So thats saying the prob of drinking the milk given the fact you ate cheerios

rapid wraith
#

Yes

granite void
#

oooh

upper karma
rapid wraith
granite void
upper karma
#

oh

rapid wraith
#

i know p(A)(B) is 1/10