#geometry-and-trigonometry

1 messages · Page 363 of 1

dire copper
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2x - 3(a + 1)y + a - 1 = 0
the slope is 2, what is a?

can anyone help?

dark sparrow
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@dire copper do you still need help with this?

dark sparrow
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do you know how to find the slope of a straight line from its equation?

dire copper
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I guess no and that's why I couldn't:(

silent plank
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would you be able to determine the slope of something like
$$2x + y = 5$$

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@dire copper

somber coyoteBOT
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ℝamonov

dark sparrow
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they DM'd me with their answer

nova tiger
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I got the equation arctan(100w)+arctan(w) = 90 degrees
From what I remember arctan(a)+ arctan(b) =arctan(a+b/(1-ab))
so what I did was to tan both sides and got a+b/(1-ab) = tan(90) which is undefined
but when I look at solutions what they did was: arctan(a)+ arctan(b) = sign(a) x 90 degrees, if ab = 1 then they set 100w^2 = 1 and solved

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so my question would be, why was the first method I was using wrong? and whats the theory behind the solution? ive never heard about it

wary veldt
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Hello all.

TLDR: My question is - how do I convert a decimal (e.g. 1.414213562 is root2) to the root form?


I'm working on a pre-calc course and getting some basic trig. It's an online class with no professor. I'm inputing sin/cos/tan etc problems in my calculator and getting decimal results where the text book is providing roots.

For example, the problem is sec(pi/4)
I input 1/cos(pi/4)
answer = 1.414213562
Book answer = root2, which comes out to 1.414213562

I think I SHOULD be correct if I answer the decimal form on the quiz / tests, however I'd rather avoid having to justify it if I can give the root version of the answer.

Sorry this is so long.

My question is - how do I convert this decimal to the root form?

old fable
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Why does the radial component of the weight have a minus sign? The force is in the r hat direction so why would it have a minus sign?

dim stirrup
old fable
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But the radial direction is towards r hat or not?

dim stirrup
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r hat is pointing away from the centre of the circle

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the acceleration is towards the center of the circle

old fable
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So radial acceleration is always to the Center of the circle

dim stirrup
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in this case, circular motion

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T is always towards the center

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the weight isn't

old fable
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Where can I find resources on this radial acceleration

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As it’s so confusing

dim stirrup
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search for centripetal force

old fable
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Yes but that’s not always the radial acceleration, I heard some dude say

dim stirrup
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im not sure what he means by that haha

old fable
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Wait I’ll send the vid

dim stirrup
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oh okay

old fable
#

Min 3:31

dim stirrup
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the tangential force in your case is given by Wcos(theta)

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so the weight always points down

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as the mass moves around the circle

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you need to split the components of that vector into radial and tangential

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think about it physically

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if the mass is at the bottom of the circle

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the weight won't make it move

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however, if the mass is at 90 degrees, it will fall down

old fable
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Oh ok

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But how do you explain what he says in the video

dim stirrup
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oh okay, so the difference here is how you're defining r hat in your model

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it doesn't actually matter, just pick whichever direction makes your calculation convenient

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whichever one you choose will only add or remove some minus signs

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it's like deciding xhat points like <- instead of ->

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doesnt matter

old fable
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Ohh ok just like he says in the vid

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Thanks a lot

dim stirrup
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no worries

old fable
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I’ve been on this for like 2 hours cuz no replied in the physics server

dim stirrup
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feel free to ping me with any physics questions, i have 2 masters degrees in it haha

old fable
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Oh damn

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I’ll sure do

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Thanks again

dim stirrup
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might be

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yes

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what do ya need lmao?

grizzled lantern
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cap

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what class is it?

dim stirrup
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high school?

grizzled lantern
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Lol

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fuck trig

dim stirrup
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show me the questions lol

grizzled lantern
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1/2bh

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?

dim stirrup
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whatever, im bored and can give you a hand with a few

grizzled lantern
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that a radius

dim stirrup
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i dont need your money

grizzled lantern
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18 is half your height

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and all the sides are the same

dim stirrup
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i failed maths in school bro i feel your pain

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alrite bro dm me the qs

plush cloud
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Help?

simple bear
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<@&286206848099549185>

dark sparrow
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@plush cloud do you still need help with this?

nocturne remnant
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E is a point on the interior of quadrilateral ABCD s.t.
[AEB][CED]=[BEC][DEA]
(where [] denotes the area of a triangle. )
Question: Is it possible that E lies on neither AC nor BD?

dark sparrow
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i can say for certain that it's impossible if ABCD is a parallelogram

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not sure about the general case tho

nova tiger
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why is arctan(a)+ arctan(b)=sign(a) * 90 degrees if ab = 1?

nova tiger
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<@&286206848099549185>

nocturne remnant
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let a=tan x, b=tan y
( -90<x,y<90 by range of arctan)

tan x tan y = 1
tan x tan 90-x = 1 (identity)
So x+y=90 or -90

If x+y=90, x and y both positive, so a is positive, done
x+y=-90 just the same

nocturne remnant
# dark sparrow i can say for certain that it's impossible if ABCD is a parallelogram

I think I have an epiphany

(Refer to diagram)
The area condition reduces to

sin a sin c = sin b sin d
(Other than trivial sols with a+b=c+d=180 etc.)

Suppose a non trivial sol exists.
Then let T be a point in the region with smallest angle in (a,b,c,d) in this case c
Then reflect Ray EA over T, it should meet EC again (since this solution is not trivial) at P, then by def P’ would be back on Ray EA
(Same for Q AND Q’)
Then PQP’Q’ is parallelogram with a nontrivial sol. Which we know cannot happen.
Done satisfiedblob

old fable
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,w simplify (-csc x)(cot^2x) + csc^3x

somber coyoteBOT
old fable
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does this actually simplify to cscx?

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looks kinda weird to me cuz the second part is way more complicated

wanton silo
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Any tips to remember trig identity

potent dove
mossy geyser
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From the dimensions of the black rectangle and the green line length, I want to calculate the length of the blue line. So, I thought maybe I should determine, first, the value of the violet angle. But how can I do that? I'm confused.

orchid quartz
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$$\frac{5230 \text{cm}}{1} \cdot \frac{1 \text{m}}{100 \text{cm}} \cdot \frac{1 \text{hm}}{100 \text{m}}$$

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$$\frac{5230 \text{cm}}{1} \cdot \frac{1 \text{m}}{100 \text{cm}} \cdot \frac{1 \text{hm}}{100 \text{m}}$$

somber coyoteBOT
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Mr Syndicate7734

silk venture
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let a=tan x, b=tan y
( -90<x,y<90 by range of arctan)

tan x tan y = 1
tan x tan 90-x = 1 (identity)
So x+y=90 or -90

If x+y=90, x and y both positive, so a is positive, done
x+y=-90 just the fuck

unreal ivy
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oh wrong channel

shell raven
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so i have a question

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if I had a circle with a radius of 1cm

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and i had a piece of string 1cm and put it around the circle is a radian

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wait no

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that's stupid

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i don't get radians

nocturne remnant
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What seems to be the problem

shell raven
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so

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uh

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how do radians even work

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like

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wait

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nvm

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it clicked

upper karma
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hey can someone just tell if this is solvable, or the info is sufficient or not

crimson dust
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I got 3 for the big circle

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what is the small one

wheat osprey
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@crimson dust how did you get 3?

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If the question had an equilateral triangle then we could have done it by finding the angle OCF... But out here there's no symmetry... So how did you go about it?

fallen girder
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2 different ways of finding the area of the triangle allows an easy way to solve for the inscribed radius

wicked crag
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how am i supposed to solve this

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"Find the value of the following, put it in its simplest form.
cos(pi/12)

wheat osprey
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We know cos(pi/6) = root(3)/2

marsh bobcat
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hey, can anyone help me with a trig question? i forgot trigonometry lol

wanton silo
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can anoyne please help me with geometry

marsh bobcat
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can i dm you?

wanton silo
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k

torn sluice
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hey guys

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I have a trigonometry question

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what do I need to do here?

silk patio
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What’s the question

torn sluice
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find coordinates? @silk patio

silk patio
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Of?

torn sluice
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idk :((

silk patio
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Then go away

torn sluice
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my teacher didnt explain anything :I

valid harbor
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sine and cosine law

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that's how

novel mango
# potent dove

hi, $\sin^2(x)=\frac{1-\cos(2x)}{2}$ youll get a telescoping sum

somber coyoteBOT
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God V2

upper karma
#

,

boreal niche
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can someone pleas help me with some bearings and scale drawings?

#
  1. A taxi travels 8 km south, then 3 km west.
    a) Draw a sketch to illustrate this information.
    b) Using a scale of 1 cm represents 1 km draw an accurate drawing to represent the above information.
    c) From your accurate diagram, determine;
    i. How far the taxi is from the starting point.
    ii. The bearing of the taxi’s finishing point from the starting point.
lone arch
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i think this geometry since its a shape but anyways can somebody help i forgot how to solve it and the answers and explinations i getting online arent helping+ i have to find area of these

vague bloom
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Uhh

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You know the formula for area of a circle?

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The formula is pi x r^2

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so in the first circle the radius is 12, so substitute it into the formula

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it would be pi x 12^2

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which is 144pi

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so for the first one the answer would be 144pi km^2

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and just repeat the process for the second circle

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@lone arch got it?

lone arch
high estuary
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Am I doing this right? Basically need to solve for c if a is 15

upper karma
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correct

upper karma
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Hey, currently learning analytic geometry and was wondering how can you find the rectangle points when all you know is the x and y values of only 2 points?

upper karma
upper karma
upper karma
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A (0,0), B (4,3)

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@upper karma

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I know the answers for the 2 possible options for both point C and D but I don't know how to get to those values nor I understand how to start solving this kind of problem.

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What's that

upper karma
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Oh it's fine 😅

upper karma
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(7, - 1), (3, -4) or (1,7), (-3,4)

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Thanks

upper karma
# upper karma Thanks

Its a square not rectangle according to these other points. You need to find the slope of the lines perpendicular to the line joining the two given points and passing through these two points. Then add and subtract the side(distance between the two given points) in the direction of these two lines.

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Thanks will try it out, and yeah I guess that's the right term for what I was trying to say ^^

lean ferry
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Can someone please explain double identities I have no idea what to do

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I have the formulas but idk how to do anything

flat tartan
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Is this the correct way to write where tan3x is continuous ?

fleet marsh
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what

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whyd i get pinged

hard geyser
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PogO literal ghost ping

fleet marsh
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im not a helper

night crown
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what's good brother

fleet marsh
upper karma
#

y da ping?

night crown
#

applied math gang

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LOL

fleet marsh
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no

hard geyser
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just read the rules dude

tacit whale
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420 degrees

night crown
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6

tacit whale
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qed

upper karma
#

Lol

night crown
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diagram says 6 degrees bro

upper karma
#

Bro. I just got ghost pinged

fleet marsh
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the answer is probably 1

hard geyser
fleet marsh
hard geyser
#

stop pinging the roles

night crown
#

who tf

upper karma
#

STOP PINGING

fleet marsh
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how are they pinging

upper karma
night crown
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@ ADMIN

upper karma
#

Uh

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I got pinged

upper karma
stuck torrent
spark stag
#

user has been banned

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move on

#

apologies for the disruption.

hard geyser
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thks nami

upper karma
#

Oh ok

upper karma
hard geyser
remote hill
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2 pings nice

gloomy trail
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How would I do this?

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<@&286206848099549185>

valid harbor
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if the lenght is x, then what is the lenght of its supplement

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@gloomy trail

gloomy trail
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2x+40?

valid harbor
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no

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try again

gloomy trail
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I have no idea

valid harbor
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when do two angles are supplementary

gloomy trail
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when they add to 180

valid harbor
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yes

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then can you deduce the measue of its supplement from that

gloomy trail
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oh 2x+40+x=180

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is the formula?

valid harbor
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no

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i'm asking the measure of its supplement

gloomy trail
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Tbh idk how the supplement thing works

valid harbor
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if <DCB = x then what is <ACD

gloomy trail
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x+ACD needs to equal 180

valid harbor
#

then <ACD is ....

gloomy trail
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IDK how to set it up to get the measure or equation for it tho

valid harbor
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substract <ACD from both sides....

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what do you get

gloomy trail
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180-ACD

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=x

valid harbor
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i rather meant substract x from both sides

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my bad

gloomy trail
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180-x=acd

valid harbor
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yes

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what is the measure of its complentary

gloomy trail
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90

valid harbor
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no

gloomy trail
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90-acd?

valid harbor
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the complementary to x...

gloomy trail
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is there a youtube video you could send me, I feel like I'm not fully grasping it

valid harbor
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no

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(do you still need my help)

pearl tendon
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Ok this might be a weird question

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How would we put this measurement into deceimal form

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11 7/8 “

valid harbor
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i really hope that your lack of responses is due to a lack of connection and not because of the fact that you are blatantly ignoring me

verbal night
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Math GRE question

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My current work is:

#
Note that A, B, C sit on the same circle centered at O so OA=OB=OC. Note also that O, B, C sit on the circle centered at A so OA=AO=AB=AC. That is, the lines drawn between the centers of either of the circles to any points are all of equal length. 
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Then the strategy I imagine would be to construct equilateral triangles and use some kind of angle complement argument to get it

upper karma
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hey

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who pinged me?

verbal night
weary hearth
#

anyone tagged me?

primal inlet
#

ping?

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okay last straw im removing all my roles

upper karma
#

Did someone ping me?

jolly hollow
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Idk who ping me 2 times?

surreal pike
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Anyone knows how to eliminate the x in this

gritty fractal
#

whos good with yr 10 maths
i need help lol

vague bloom
#

Post the question here.

worn sparrow
gritty fractal
lone copper
lone copper
# gritty fractal

For question 1 find a word to describe OA and OC (remember O is the centre of the circle). For question 2 just compare the length ratio of the sides and whether it increases or decreases

storm heath
storm heath
# gritty fractal

Q2) Answer is +3 since dividing the sides of the bigger triangle by the smaller triangle give that.

undone totem
versed river
#

sen is how sin is written in some spanish adjacent languages lol

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its not a typo

undone totem
sleek prawn
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and ab=cd i think

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and both triangle

full dome
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im a bit confused

quick cedar
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do you know what it means for two angles to be supplementary?

full dome
#

i solved it, nevermind

left lake
humble pulsar
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it was a prompt for Viper

left lake
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nvm I'm dumb occasionally

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thanks for clearing my confusion @humble pulsar

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I didn't realise

upper karma
#

@surreal pike still looking for help?

upper karma
storm heath
#

Lmao.

storm heath
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Well sure.

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Yee.

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I have studied that better.

potent orbit
#

Hey guys! I'm in a kinda odd situation

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My professor gave me this question and everything that has been given to me doesn't work, even what the professor gave me doesn't work and i don't know what to do

river vortex
potent orbit
river vortex
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Is there any kind of weird order you have to put them in

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I don't see why

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But worth a try

potent orbit
#

That's an old pic btw, I fixed (b), but c is messed up

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All I have for c is AB, AC, BC

undone totem
#

helppp

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nvm i solved it

nocturne remnant
#

Such as BE?

potent orbit
#

In the meantime, I gotta figure this out and I think I'm going the wrong direction

silent plank
#

ABC and ACD aren't lines

potent orbit
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Yeah, realized that a little late

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I've been brute forcing some of it for a while

silent plank
#

can you identify two lines that are perpendicular to each other?

potent orbit
#

I'll be honest, I've forgotten so much

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All I remember is that it sums up to intersecting lines that result in a right angle

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Like a plus sign

silent plank
#

perpendicular lines meet at a 90° angle

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can you identify pairs that meet at 90°?

potent orbit
#

So like AB, BC or AC, CD

silent plank
#

yes

potent orbit
#

wait

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god damn

silent plank
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its unclear how they want you to enter the answers

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try
AB||BC
AC||CD

potent orbit
#

jeeeeezzzzzz, why is this so weird

potent orbit
#

@silent plankHey, so I fixed it, but I'm on one last question

surreal pike
#

@surreal pike still looking for help?
@upper karma YES PLZ

full dome
#

can someone please draw thsese instructions with a straightedge and compass

#

Open the compass more than half the length of line
Then keep at the two ends of line and draw an arc from both sides on both above and below the line
The arcs drawn will intersect at a point above and below the line
Join the two points, this is the perpendicular bisector of the line

silent plank
#

@full domehave you tried doing it yourself

full dome
#

i dont have a compass so i cant

silent plank
#

use a cd

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fk sry for random ping

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<@&268886789983436800>

full dome
silent plank
#

compact disc lol

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blu-ray disc? but way cheaper

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or a decent sized round object will suffice

full dome
#

something like this?

silent plank
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yes

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very good

slender wasp
#

yes, and remember cos(x+pi) = - cos(x)

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Actually finding an expression for cos(2pi/5) is a slight pain :(

slender wasp
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Oh, that's easier then

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I would basically just say it's 27pi/5 shifted by multiples of 2pi until its in (0, 2pi)

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Oh sorry silly mistake

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Ignore that please I made a mistake cri

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OK so we already had that cos(27/5 pi) = cos(7pi/5) from what you said

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the trick I'd use next is the symmetry of cos x

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(about pi)

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cos(2pi-x) = cos(x)

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This is because we need to get something in [0,pi]

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Limitation on cos^-1's range ye

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A number x in the interval [0,pi] such that cos(x) = cos(7pi/5),yes

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Ye

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Well with sine it's slightly easier as the range of arcsin is [-pi/2,pi/2]

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cos(x) = cos(2pi-x), sin(x) =sin(pi-x)

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Ah okay

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Oh I mean those are correct

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But that's not what you were quoting / what we were using

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Well we were using cos(2pi-x) = cos(x)

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The identities there use + signs

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Different thing

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And sorry I can't vc

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We used cos(2pi-x) = cos(x) to say cos(7pi/5) = cos(3pi/5)

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Not the 2pi+x identity or anything

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Although yes, you used the identity with 2pi+x earlier too to get to 7pi/5 in the first place

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Yes

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yeah

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so here I'd use the sin(pi-x) = sin(x) identity

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It's not the same thing, no, it's just another identity

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Npp

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a lot can be derived from just staring at the graph, like lines of symmetry

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For example cos(2pi-x) = cos(x) because of symmetry about pi

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but you could also find another list of identities ofc if need be

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But yeah np

lusty plover
#

Quick question, what are a 3d vector's version of magnitude and direction and the equations to convert them into their components?

silk patio
#

What would you guess

dark sparrow
#

@slender wasp did someone delete all their messages after talking to you or did they get b&

thorn finch
#

I have maybe a little Advanced question

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I have some part of a circle, which is controlled by the Korde, is there a formel, which Can determine if i have moved 1cm on the “korde” from the begining i have then moved x degrees, but if i move 1cm on the “korde” from the middle i have then move Y degrees. Y > x

nocturne remnant
#

You mean, move the Korde without changing its direction? …So it gets shorter near the edge and longer near the center?

thorn finch
#

Yes. Start point is the left side of the “korde”. And the middle of the circle is static point, if i am walking on the “korde” and i start from the begining, if i move 1cm i have example made 1 degree, but if i am in the middle and move 1 cm from the same “korde” i have now by moving 1 cm made 5 degree change

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Hope that made sense 🙂

dark sparrow
#

the english word for korde is chord

thorn finch
#

Thanks 🙂

nocturne remnant
#

That sounds interesting

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I’ll try

thorn finch
#

I also try haha, it is a little brain twister

dark sparrow
#

it's going to take some calculus

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maybe? idk

nocturne remnant
#

I think I did it without calc

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The A represents the area of obtuse triangle

thorn finch
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I’ll try it out

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I have a question, if You calculate the area of the obtuse triangle, what is the degrees then

nocturne remnant
#

?

thorn finch
#

I need to calculate the length of the arc, if i move 1cm on the chord i have moved example 1,5cm on the arc from the start, and also the degrees, if i move 1cm from the start i have moved 2 degrees but if i move 1cm from the middle of the chord i have moved 8 degrees

#

But Your illustration helped me alot

nocturne remnant
thorn finch
#

Is there a Way You Can show that in a formal, where i get Y and not A, and im super grateful for Your help

slender wasp
thorn finch
#

@nocturne remnant i solved it only thanks to you mate :)! thank you

old fable
#

2/L sin^2(pi nx/L) where can i find the graph of this function

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if i put it in wolfram it doesnt give the graph

silent plank
#

what's n and L

old fable
#

constants

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but nvm

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i found it already

peak mesa
#

So idk how to explain this but the black body and the orange arm are connected so if the position of the black body changes, the orange changes too, and when the rotation of the orange thing changes, is around of the right side of the black body according the red circle (the rotation) but i want to achieve a state when the orange thing is all the time poiting to the green point independ the rotation (the black body can move or something), so i need to know what i can do to achieve this (i dont know what math i need to use on the rotation of the arm & position of the black body)

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i tried to use sin cos for the rotation of the arm and then the black position add sin/cos but inverted but did not work as expected

peak mesa
#

lol i just added 180º on the arm and thats it...

upper karma
#

In 2nd question, slope (m) tends to infinity at point (1,2). Can't use point slope form to derive the equation of tangent... Any other way?? <@&286206848099549185>

wanton kestrel
#

so you may continue that here instead

upper karma
wanton kestrel
#

i would say it's a calculus question, actually

upper karma
#

Yeah a bit of differentiation is also used

wanton kestrel
upper karma
visual girder
#

where do i begin to solve this triangle?

steel trout
#

Whole triangle - top triangle = bottom quadrilateral

flat schooner
#

can someone plz explain what this is and how it works? |

visual girder
#

how do I find angles ACB and DEC

upper karma
dark sparrow
#

no, i think it was "stolen" from a greek word

surreal pike
#

Help i need to find the area of the colored area in the unit circle

#

And also say true or false and justify

potent orbit
#

dis sucks, any thoughts?

storm heath
#

Any way to know the reason why their graphs is such without knowing radians and stuff?

dark sparrow
#

@storm heath suck?

#

what do you mean

storm heath
#

Edited.

#

I meant "such" instead of "suck".

nocturne remnant
#

How such?
They look normal to me

dark sparrow
#

yeah these do not look weird to me

#

but desmos does measure angles in radians by default

#

there is a setting to make it use degrees instead

storm heath
#

I mean to say.

#

What is the reasoning behind them.

nocturne remnant
#

.?

#

Behind what

storm heath
#

The graphs.

#

What else.

nocturne remnant
#

Hmm

#

Do you understand the sine one

storm heath
#

Npe.

#

Nthing.

#

Must I learn Radians?

dark sparrow
#

you're just starting trig right

storm heath
#

T understand these?

storm heath
dark sparrow
#

okay then you'll learn everything in due time

#

radians are just a unit of angle measurement nothing more

storm heath
#

Damn inverse trigonometry is cool but hard.

dark sparrow
#

get comfortable with right triangle trig and circle trig will follow

potent orbit
#

I hate this math

potent orbit
#

It's due in 30 minutes and I have an english paper due in 30 minutes too

dark sparrow
#

@potent orbit and you want us to do what about that, exactly?

potent orbit
#

My questions are slightly easier than what you're dealing with rn

storm heath
#

GiVe DiReCt AnSwErS.

potent orbit
#

whatever, I have 7/9 total

#

Look, I need a, c and d. I can't really figure this out

storm heath
#

What the duck is this inverse trignmetry.

#

Fun but hard.

potent orbit
#

my stuff or your stuff?

storm heath
#

My stuff.

dark sparrow
#

...your part (a) looks weird to me

#

no clue what conclusion they expect you to draw from a=e

potent orbit
#

Yeah...

#

this is why I've been stresdsing

nocturne remnant
#

Then e=a?
Seems like the only reasonable thing flonshed

potent orbit
#

Tried

dark sparrow
#

at least c and d are somewhat more transparent since the angles in question are well-positioned

storm heath
#

Yeah exactly.
What is angle of s's?

potent orbit
#

I've even done b=e/e=b

#

just.. c/d is confusing

dark sparrow
#

(c) you can look at angle 3

#

(d) you can look at the sums of two pairs of angles

#

thats as much as can be said without just giving away the intended answer\

potent orbit
#

I'm so confused, I'll get to you if I fail the question or get it

#

Oh yeah, I also have this too

storm heath
potent orbit
#

I got it partially corrrrect

storm heath
#

Ayo wtf.

potent orbit
#

i was thinking of only one pair instead of actually using multiples

dark sparrow
#

D nt yu think ❓how-to-get-help wuld be better since that place is mre fr help than discuss?
is your O key broken?

storm heath
nocturne remnant
storm heath
#

I need t use this but it is tedius.

nocturne remnant
#

The 45 degree diagonal line

storm heath
#

I see.

#

But-

nocturne remnant
#

Actually, for any function f, the inverse of that function should look like it’s reflection over the diagonal line
(Disregarding the domain stuff)

storm heath
#

This yu mean?

verbal beacon
#

no ,the line y=x

storm heath
#

Duck I need t re-learn Algebra 1 which I started and get inverse trignmetry well.

storm heath
verbal beacon
#

you've sent a diagonal of a square

storm heath
#

Cnsider the square the graph ff.

#

But tan 35/65 is 0.0093 smething.

storm heath
woven yacht
#

.

desert pewter
#

i just asked a triangle question in #help-6 if anyone can help

lone cave
lone cave
#

,help

somber coyoteBOT
#

A brief description and guide on how to use me was sent to your DMs!
Please use ,list to see a list of all my commands, and ,help cmd to get detailed help on a command!

verbal night
#

Does anyone have hints on how to do this?

#

math GRE question for context

valid harbor
#

@verbal night impossible

verbal night
#

This is how I feel every single time I like at a MGRE geometry question

sour folio
#

can someone help me with transformations

spark stag
humble pulsar
#

even/odd ness of a function is a property of the function

#

so doesnt matter

junior veldt
#

Idk how to help without giving answers, but I’d suggest to think of how midpoints work? (Given can be a thing you put in reasons)

#

Look at 3

upper karma
#

how do i evaluate this

#

Sin(arccot(1/2csc(2pi/3)))

verbal night
clever sluice
#

Can anyone teach me how to evaluate the volume of a spherical hexagon given its angles and sphere radius?

lone cave
#

Been struggling on this one for days now

Given: ray OP (pointing right) and ray OR (pointing right) trisect ∠NOS, m∠NOP = 3x - 4y, m∠POR = x - 6, and m∠ROS = y - 10. Find the m∠ROS by creating and solving a system of equations.

molten delta
lone cave
#

yes but i do not know how to set it up

lone cave
ocean socket
#

Oum Hi

wary veldt
#

Hello all,

My text book has not explained how to complete these problems. I was wondering if someone would be willing to walk me through the process with problem 38

#

Or any of the even numbered problems really, as the answer key in the book only covers the odd numbered

#

Disregard - I've figured out to find the x/y intercepts

valid harbor
#

The slope of the line represents the tangent of the angle made by the x-axis and the lane

#

@wary veldt

solid mantle
#

Can anyone explain how it’s rad3 from tan60?

lone copper
#

Special right-angled triangles in trigonometry, there are mainly 2 to remember, for this one just draw an equilateral, draw a line from the top vertex to nicely ÷ the triangle into two smaller triangles, ratio of hypotenuse: smallest length=2:1
Now use pythagoras theorem to find the opposite length and tangent ratio is opposite/adjacent=√3/1=√3

upper blaze
#

Hy guys, does anyone know any good book that has stareometry and properties of pyramids and stuff?

upper karma
lone copper
#

Seems correct

#

I think it cannot be factorised

hallow tulip
#

If it only gives you that information you could theoretically say that:

#

$\tan{\theta}=\frac{\sin{\theta}}{\cos{\theta}} then \sin{\theta}=2x(x+1) and \cos{\theta}=2x+1$

somber coyoteBOT
dark sparrow
#

no you couldn't say that

#

who says 2x(x+1) is between -1 and 1

#

or that 2x+1 is between -1 and 1

solid mantle
#

Can anyone help explain how they got that answer? Plugging it into the calculator also seems to be wrong

upper karma
#

,w approx 1/(sin(25 degrees))

somber coyoteBOT
upper karma
dark sparrow
#

👻

kind rain
#

I need help with this

kind rain
#

<@&286206848099549185>

valid harbor
kind rain
valid harbor
#

very good reply tho

#

also is that a test

kind rain
#

No

#

It’s homework

raw tiger
# kind rain

a segment bisector is just a line/ray that divides a segement in half

split nexus
#

can anyone help me on my hw

left lake
#

go ahead and post the question

#

someone can help

nocturne tusk
#

for geometry, to have an opposite ray, do the points have to be on the same line?

storm portal
#

If (in 2D), a ray with a starting point has an opposite ray, then I'm pretty sure they lie on the same line

#

The opposite ray may or may not be able to have its starting point elsewhere.

lone copper
#

Split the top circle into a semicircle

#

Then the bottom part of the top circle not overlapping with other circles=area of square with sides 1cm- area of quadrant with radius 1cm

#

Each side of the blue square is 1cm

#

So u can find area of black portion by taking 1²-area of quadrant

lone copper
#

Send ur workings u r probably doing something incorrect

#

Yes

#

That is an even better diagram than mine

#

So it’s (2+area of one circle)cm²

#

It’s ok we are always careless

#

As long as u understand where u went wrong, ur good

#

Np

lone cave
smoky talon
#

tell me if ur good at 2 column proofs

junior veldt
smoky talon
#

yeah

junior veldt
#

if you need helpw iththem, i might be able tohelp wtih simpler ones? i could try

smoky talon
#

k

#

i need help with hard ones, ez ones are ez

junior veldt
#

which ones are the hard ones? i could try to help with them?

fluid wasp
#

quadrant VI is the same as quadrant II? angerysad

dark sparrow
#

i think they meant quadrant IV but typo'd

pure void
#

hi

#

i need help with math xdd

timid pier
#

a question specifically or a concept?

pure void
#

like conditional

#

and stuff

#

@timid pier pls help me understand this better

timid pier
#

aaa sorry but i have a limited understanding on geometry stuff, idk this stuff

#

sorry

pure void
#

oh i forgot to add false

upper karma
#

I had a question

#

Do you know what cosec is

#

Yes

#

Do you know what cot is

#

Yes

#

Trigonometric ratios

#

Do you know that sin^2 t + cos^2 t = 1

#

Yes it's an identity

#

Did you try expressing cosec and cot in terms of sin and cos and using this identity to simplify your expression?

#

...lemme do again. It all messed up

#

Oh. I see

#

Like this?

#

Yes, exactly

#

Then should I square them

#

Yes

#

Did it

#

Alright.

#

Yeah. Now plug it in and simplify

#

Oo lemme try

#

But how

#

🤔🤔

#

First, multiply nominator and denominator by sin^2 A

#

Okei

#

Now

upper karma
#

The denominator :- sin^4 A

#

Should I solve numerator part by quadratic equations formula?

upper karma
#

Show me your calculations

#

Okei

#

It's not this that you were supposed to multiply

#

I meant (q^2-1)/(q^2+1)

#

Plug in q^2 and multiply nominator and denominator by sin^2 A

#

@upper karma and how is it going?

upper karma
upper karma
upper karma
winged torrent
#

How the frick did i forget dis property

#

can someone help

junior veldt
#

I think (this is my guess) that if both segments are the same length then the other 2 angles should be the same? So like 180-100 then take whatever you get and divide by 2?(this is a guess)
@winged torrent

winged torrent
#

yyah i just forgot the property btw the answer is 40

#

can someone help on this

#

<@&286206848099549185>

junior veldt
#

There’s a supplementary angle in there

#

Use it

junior veldt
# winged torrent

Use supplementary angle theorem thing to find angle ABC, then go on from there

winged torrent
#

ok

#

thnx

bitter nimbus
#

<@&286206848099549185>

#

someone please help

raw saffron
bitter nimbus
raw saffron
#

ok

#

so angle B is 55 degrees due to corresponding angles

#

and angle A is 125 degrees

#

@bitter nimbus

bitter nimbus
#

ohhhhh

#

okay thank you so much

upper karma
#

Hello

#

Anyone free?

#

I wanted help

dark sparrow
#

@upper karma do you still need help with this?

upper karma
#

Still?

#

It's a new one

dark sparrow
#

maybe you could have had an idea in the 5 minutes before me noticing it

#

in any case, what's giving you trouble here?

#

it appears all you'd need to do here is substitute the values of x, y and z into x^2+y^2+z^2 and simplify.

slender wasp
#

because it's multiple choice just consider A = 0 bad advice

nocturne remnant
# upper karma

Obviously the answer is proportional to r^2
So that leaves A or B
Subbing r=1, a=b=0 gives the answer is B

dark sparrow
#

or you could also not engage in any of that bullshit

#

it is not hard to simplify r^2 sin^2(A) cos^2(B) + r^2 sin^2(A) sin^2(B) + r^2 cos^2(A) using the sin^2 + cos^2 identity twice

nocturne remnant
#

Or…pandaThink
You can prove with actual geometry

elder pebble
#

pls help

winter rover
#

Hey could yall help me with some geometry problems? They're pretty basic

lyric topaz
#

hi guys i was wonding i my question is right

#

My classmate said it is incorrect

junior veldt
#

For first 8magem do you know what alt int and alt ext angles are?

winter rover
#

I know what they are, but I don't know how to explain them.

junior veldt
#

For sending image, use the supplementary angles

junior veldt
storm heath
#

Anyone here who has studied AoPs Introduction to Geometry?

noble thunder
#

Introduction to Geometry?

#

didn't saw that before on aops

#

is that a pdf or a post

#

oh it's a book from aops...

#

it says for grade 7 to 10... I don't think it could be very advanced though I never read it before

upper karma
#

please help

quiet blade
#

If you need a hint, start with the fact that the center of the incircle and (one of the*) smaller circles must lie on one of the angle bisectors

upper karma
somber coyoteBOT
#

OvercomplicatedHexagonAAAAAAAA

quiet blade
#

yes the result generalises to the other circles as well

#

but only one small circle* would lie on the angle bisector of A

upper karma
#

yeah ok fair enough

#

how to do this?

#

https://www.youtube.com/watch?v=baD79KCWcsQ
@quiet blade btw what the hell is this lmao
i assume this is wrong?

There are 4 incircles of respective triangles given in the figure, GH||AB, IJ||BC & JK||AC , Radii of circles with centers O, M and Q are 1, 2 and 1.5 unit respectively then what is the radius of the biggest circle (in-radius of △ABC)

Your smartphone is your classroom- Download Android App - http://bit.ly/3Eapp

How Can I Ask Questions To Ami...

▶ Play video
#

@upper karma could you perhaps help?

#

sure

#

ty

#

as $MQN$ is similar to $MPO$
\$\frac{MQ}{MP} = \frac{MN}{MO} = \frac{QN}{PO}$

somber coyoteBOT
#

OvercomplicatedHexagonAAAAAAAA

upper karma
#

just substitute values now

#

ah okay ic ic, i was just confused as to what is similar to what etc

upper karma
upper karma
#

is this what I should get after substituting the values?

#

@upper karma ^

upper karma
#

edited

#

still seems wrong

upper karma
#

$MO = 6 + \frac{18}{5} = \frac{48}{5}$

somber coyoteBOT
#

OvercomplicatedHexagonAAAAAAAA

upper karma
#

so $\frac{MN}{MO} = \frac{6}{\frac{48}{5}} = \frac{5}{8}$

somber coyoteBOT
#

OvercomplicatedHexagonAAAAAAAA

upper karma
#

ohhhh

upper karma
upper karma
#

lmao

#

ok so im getting 5/8 = 5/8 = x/x+9/4 @upper karma

#

i really appreciate the help btw

#

nice

upper karma
upper karma
#

so from now on, what do I have to do?

upper karma
#

kk lemme do that

upper karma
#

i think so yes

upper karma
#

:)

ruby seal
#

i need help calculating the circumfrance and the area of a circle

#

no questions just revison

sweet linden
#

iirc,
Circumfurence = 2 * pi *r
Area = pi * (r^2)

eternal plover
#

Why does the circle have to move when graphing trigonometric ratios?

#

nvm I think I get it now

slate steppe
#

Could someone help me with this? I’m stuck on 24

onyx cloud
#

can we assume that OZ is parallel to OB?

slate steppe
#

Most likely yes

onyx cloud
#

actually i don't know if that's helpful

#

the immediate thing i see is that AOZ looks like a 90 degree angle

#

but i can't quite show it is with the information they gave you

slate steppe
strange river
#

Um hello?

onyx cloud
#

hello

strange river
#

Do you know how to do this?

onyx cloud
#

yes

#

do you know what the area of the first siren would be?

strange river
#

About 5.3

#

I think

onyx cloud
#

ypu

#

yup

#

1.3^2 * pi, correct?

strange river
#

Yes

onyx cloud
#

so what we did there is
A = pi*r^2

#

and we solved for the area

#

now, instead, what we want to do is solve for the radius

#

if the area is double what we had before, we can set A to be 2 * pi * 1.3^2

#

so

#

2 * pi * 1.3^2 = pi * r^2

#

can you solve for r here?

strange river
#

10.6 is the new area right?

onyx cloud
#

it's best to keep it exact

onyx cloud
strange river
#

Ok

slate steppe
#

Could someone help me understand this?

#

I’m really bad at proofs

#

I need help solving it but I also want to understand how to do these on my own

storm portal
#

Well, we can say that CT = CA + AT

#

And there for CT = DO + OG

#

because CA = DO, and AT = OG

#

And because CT = DO + OG, and DO + OG = DG

then CT = DG

upper karma
#

i have a question - sec411º to rounded two decimal places

#

can anyone show me steps for this?

silent plank
#

do you know what sec(x) is?

upper karma
#

i've seen it but i dont know much

#

i think i heard there is a way to solve it with calculator?

silent plank
#

yes

#

but in most cases will require you to know the definition of sec

#

$\sec(x) = \frac{1}{\cos(x)}$

somber coyoteBOT
#

ℝamonov

upper karma
#

oh

silent plank
#

which is something that could be entered in a scientific calculator

#

also make sure it is set to degrees since you're working with degrees

upper karma
#

ty so much ill try that

#

can i ask one more question?

#

secØ<0, sinØ<0 sinØ<0, tanØ>0

#

i have to name the quadrant where the angle lies

silent plank
#

don't use Ø as a variable (assuming you're using it in the place as theta)

#

the simple letter t is a much more appropriate substitute for theta

#

have you done much with the unit circle yet?

upper karma
#

no we just started with this chapter

silent plank
#

not much or literally nothing at all?

upper karma
#

i should say nothing at all

#

i've never seen one of these

silent plank
#

i mean you should at least have some information since,
work with quadrant is dependent on knowledge of the relation between trig and circles

#

otherwise the teacher hasn't provided you with the information required to do this

upper karma
#

oh this isn't a assignment that's due i just wanted to look ahead what we were gonna do

silent plank
#

try to find an in-depth guide on the unit circle and its properties

upper karma
#

ok

timber tapir
#

how do you know what specific values of a trig function

#

?

#

in high school covid kicked me out of school when we covered the unit circle

#

and idk how ppl just look at sin(pi/2) or sin(0) and know what it is

weary drift
upper blaze
#

Guys there is one interesting problem I am working on 😄 If anyone has any ideas it would be apriciated. I got a bit rusty on those stuff 😄 I will post a picture too 🙂
Problem: Equilateral triangles $\triangle A_1BC, \triangle AB_1C, \triangle ABC_1$ are constructed outwards on sides of triangle $\triangle ABC$ and equilateral triangles $\triangle A_2BC, \triangle AB_2C, \triangle ABC_2$ are constructed inwards on sides of triangle $\triangle ABC$. Let $A_0,B_0,C_0$ be midpoints of $BC,AC$ and $AB$ respectivly and let $C_3$ be midpoint of $A_1B_1$. (With $A_3$, and $B_3$ you can mark midpoints of sides$ B_1C_1$ and $A_1C_1$ if needed). Also let $A_4$ and $B_4$ be midpoints of $B_2C_2$ and $A_2C_2$ respectivly (you can set $C_4$ the same way). Prove that triangles $\triangle A_4B_4C$ and $\triangle A_0B_0C_3$ have the same center.

somber coyoteBOT
#

MotionMath

upper blaze
#

Two things I know for sure ahha Both of those triangles are equilateral and C C_2 anc C_3 are colinear

#

and CC_3=C_2C_3

upper blaze
#

I think you just need to memorize just value of sin of angles 30 45 and 60

#

all others you can deduce from those 3

timber tapir
#

really? how

upper blaze
#

well 0 and 90 are 0 and 1 always on sine and cosine

#

cosx= sin(90-x) so you got cos 30 45 60 from there

upper blaze
timber tapir
#

wait what im lost

upper blaze
#

HAhaha

timber tapir
#

sorry im not good at trig stuff

#

if u can't tell

#

but that's why im here

upper blaze
#

values at 0 90 180 360 are always 0 or 1 in sin and cos

timber tapir
#

ok

upper blaze
#

and you just need to understand where you look cosine values and where you look sin values to know them

#

so those are easy

#

you go that?

#

and 270 same

timber tapir
#

"where you look cosine values"

#

idk what you mean by this

upper blaze
#

Hmm, when you draw unit circle, you look cosine values on x-axis and sin values on y-axis

#

you know that?

timber tapir
#

i do now

timber tapir
#

last half of precalc got cancelled

upper blaze
#

Now when you got like cos(90) its easy just remember cos is on x axis and you immidiatly know thats 0 😄

timber tapir
#

ok so i know the thing where the denom is 0 and the numerator is 1,2,3 and 3,2,1 then sqrt everything

upper blaze
#

hmm ok I dont get what you want to say on this xD

timber tapir
#

idk it's like a trick to remember something my teacher showed

upper blaze
#

Hmm you in high school?

timber tapir
#

no im in college

#

i passed calc last year in high school and got the college credit but i wanted to take it again in college just to make sure i have a solid foundation before hitting calc II

upper blaze
#

Hmm Idk maybe this works for someone but I wouldnt learn this method honestly haha

timber tapir
#

okay

upper blaze
#

but you can to this too if you see its good for you

timber tapir
#

so teach me the way of the unit circle

#

pls haha

upper blaze
#

DId you understand what I said about 0 90 180 270 and 360 first?

#

those should be easy

timber tapir
#

sure but i usually see the values in radians

#

so it would b easier to convert to that bc i more often end with like sin(pi/2)

#

than sin(what ever pi/2 is)

upper blaze
#

okay I can do that 😄

#

so we are done with those values

#

now all you need to learn

#

is sin(pi/6) sin(pi/4) and sin(pi/3)

timber tapir
#

so they're always 1 or 0, so i just need to memorize which are 1 and which are 0?

upper blaze
timber tapir
#

wait is pi/2 the angle at (0,1)

#

ar

upper blaze
timber tapir
#

ok so now what

#

like idk where to even start to understand the unit circle

#

like i have a circle drawn with x and y axis in front of me

#

in my notes

upper blaze
#

Uhh seems to me like you miss theory there :/

timber tapir
#

huh?

upper blaze
#

The way I teach trigonometry is that I ask my students to understand sin and cosine functions completly

timber tapir
#

okay well i am willing to learn that

upper blaze
#

and how to connect them from right trigangle to unit circle

timber tapir
#

yes i just have very little understanding of the unit circle bc of aforementioned reasons

upper blaze
#

Well for values that you asked not much is needed actualy

timber tapir
#

yeah but i dont want to just learn for this test

#

like ideally i'd like to understand the unit circle

upper blaze
#

you know that it is and you know what points determines 0,pi/2,pi,3pi/2 and 2pi points right?

timber tapir
#

no

#

all i know is the info from the vid i sent

#

which is the angles and their coordinate values

upper blaze
#

good

#

now

#

When you want to find values of sin function

#

you always look at y-axes

#

for example

#

wait I will draw you picture

timber tapir
#

oh so (x,y) is cos, sin

upper blaze
#

yes 😄

timber tapir
#

ok nice

#

good to know

upper blaze
#

okay and now

#

when you have sin0

#

you need to see what values is determined on y axis by its 2nd line

timber tapir
#

wait so what are the coordinates of pi/2

upper blaze
#

pi/2 is at x=0 y=1 so (0,1)

#

1st line of angle is always on positive part of x axis

#

Look at this picture

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orange part is value of sin and pink one is cos value of angle that I draw there

timber tapir
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ohh yeah duh

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so do i only need to know the angles for that one quadrant?

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and then i can just make x and/or y negative based on whichever quadrant im in?

upper blaze
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Basicly yes

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you just need to be very careful there and thats it

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And you dont need to know both sin and cos

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you just need one

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I memorize sin in first quadrant

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and rest I deduce from formulas and using this fact that you look sin on y-axis and cos on x-axis

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Thats how I do at least

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when you give me an angle it takes max 2s to deduce but thats becouse of practice though at begining it may take you 5-10s to calculate in your head or its even good to draw a picture for yourself

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dont be afraid of doing it on the little picture on the side of your paper

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its better to understand how it works than to memorize that table honestly

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its more valuable for you

timber tapir
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yeah i think for now i will def draw the picture when i need to

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thank you

upper blaze
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I really dont know what book is good for it though

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I have never learn that from book

timber tapir
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so then i find tangent with trig conversions

upper blaze
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tan=sin/cos

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nothing else you need honestly

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those sqrt(3) stuff I have never learned in my life xD

timber tapir
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like if i need tan(pi/2), i do cos(pi/2) [0]/ sin(pi/2) [1]

upper blaze
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yes

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basicly

timber tapir
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well thanks i hope that works

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wait

upper blaze
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the one I know though is arctan 😄

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but you probably dont need those

timber tapir
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what's the angle at (1,0)

upper blaze
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its 0

timber tapir
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oh ok

upper blaze
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both lines coincide

timber tapir
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so the pi/2 angle is the 90 degrees angle

upper blaze
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yes

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those radians is best to learn just pi=180 😄

timber tapir
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wait so when would i ever use (-1,0)

upper blaze
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thats pi

timber tapir
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oh so 1,0 is 0 and -1,0 is pi

upper blaze
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Thats when one line of angle is positive part of x axis and 2nd on negative part

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yes

timber tapir
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what about 0,-1

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-pi/2

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?

upper blaze
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3pi/2 or -pi/2

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yes

timber tapir
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ok this makes sense

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thank you again

upper blaze
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np anytime 😄

timber tapir
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im glad i finally understand the unit circle

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its been haunting me in calc haha

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every time i see a lim and then a trig function

upper blaze
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Hahahah just practice it every time you need it

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and after 10 uses you will do it blindfolded 😄

prime vigil
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hey i need help

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i was sick and missed my lesson

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so i need help with this geo review