#geometry-and-trigonometry

1 messages · Page 75 of 1

fast geode
#

Love these problems

#

Easy

obsidian harness
#

ezpz

fast geode
#

mhm

weary shoal
#

Anybody know the name if the geometry bc i got a test on monday and i do NOT understand this

covert mango
jade sierra
#

what do i do 😭

#

i only get to the part where you add u and v but not find the rest

faint hollow
#
  1. $|u+v| = \sqrt{u^2+v^2+2uvcos(\theta)}$
somber coyoteBOT
#

Black_Gold

faint hollow
#

where $\theta$ is the angle between two vectors

somber coyoteBOT
#

Black_Gold

jade sierra
#

I’m sorry but I came from alg 1 last year 😭

jade sierra
trail tendon
jade sierra
#

This feels like a whole new class 😭

trail tendon
#

wait lemme fix

faint hollow
#

now to find the angle use --> $tan(\alpha) = \frac{usin(\theta)}{v+ucos\theta}$

#

where $alpha$ is angle between v and u+v

somber coyoteBOT
#

Black_Gold

faint hollow
jade sierra
#

what does the weird 0 mean

somber coyoteBOT
#

Black_Gold

jade sierra
faint hollow
jade sierra
#

Well as it happens I have 4 angles and I don’t know which to pick

faint hollow
jade sierra
#

I just started trig idk what’s derivation

faint hollow
#

do you want to know where these formulas came from??

jade sierra
#

Sure

faint hollow
#

the second one

#

sorry for the poor camera quality

toxic linden
#

can someone pls explain how the formula of the cone works?

hoary totem
#

so the volume of a right pyramid is 1/3 of a rectangular prism

#

turns out this is true for any base shape though, not just squares (pyramids; rectangular prisms)

#

hence the volume of a cone is 1/3 of the volume of a cylinder

toxic linden
#

aight thank you

broken nova
#

can anyone send class 11th cbse trignometic funtions questions

minor pawn
bright pecan
#

why does this not work?

#

thank u

#

we r year 9s

minor pawn
#

ty

minor pawn
bright pecan
#

basically u need to do some intergrals stuff

#

beyong my capabilities

minor pawn
#

alright.

faint hollow
# bright pecan

If you are taking the side of triangle 'r'(same as cone's radius) then at that point it's no longer a triangle, it's side on circumference would be arc

jolly shore
#

This may help you guys

plucky cargo
#

moew meow help with this one one

obsidian harness
plucky cargo
#

thxx

faint hollow
wintry yacht
#

Q3

obsidian harness
#

so BF/BC = GE/GA

#

or that BF/1 = 1/GA, as GE = EA (isosceles) = 1

obsidian harness
#

now since GA = x, that implies BF = 1/x

wintry yacht
#

Ohh kaaay

#

Thankyou

obsidian harness
#

npnp

covert mango
dire mirage
#

Help pls

#

If its an isosceles then I can split it up into 2 right triangles right?

#

And since its congruent on all sides that must mean the angles are the same right?

#

But somehow my answers are wrong

silent plank
#

can you show your work/calculations

dire mirage
#

Phone is dead so I cant at the moment

viral mauve
bright pecan
faint hollow
#

Wait let me think

vagrant snow
#

And each angle of an equilateral triangle has the same angle which is?

worthy tendon
#

so you have to kind of cut the triangle into pieces that travel the same distance and multiply the area of that piece with the distance it travels... until you are done with multiplying all the pieces

jade gyro
# dire mirage

the middle angle is 60 degrees. since AB is straight line, the angle to the right is 120 degrees.

since the triangle with 120 degrees is isosceles, x = 30

lime crownBOT
jade gyro
#

ooh i thought we were supposed to give out solution

undone quest
#

Ar(ABC)

faint pasture
# undone quest

Uhhhh one way is to apply the cosine rule in ADB and CDB and solve for CD and BD

#

Now you have three sides

#

And you can just use the herons formula

#

Tho i think there should be a better way

polar cypress
#

Can anyone help 😭

#

I’m dumb

#

Kay

#

Second….

#

ANSWERR PLS

#

😔

#

I will after I sleep oh yeah!

#

Get out

#

🧌

#

….

#

Is it dead

#

Weird cat…

#

Mine sleeps like a normal cat

#

Lalalalalalalala

#

I choose no thanks

#

Sigh fine

#

Buh bye..

spiral hare
undone quest
#

@faint pasture I actually dont know law of cosine

#

Though that way is quicker

#

I figured it out

faint pasture
undone quest
#

We can assume h

#

Height

faint pasture
#

Ye

undone quest
#

In base of triangle

#

And then pythagorus

#

Eqn1 and eqn2 subtracting

#

But thank u

faint pasture
#

That sounds kinda like the derivation of the cosine rule

#

I mean not exactly

undone quest
#

Yup tup

#

Premath uploads these type of questions

#

But his question solving is complex

toxic linden
#

Why is the volume of a cone half of the volume of a sphere. We are in 9th grade

toxic linden
#

no like

#

of the same radius

faint pasture
#

1/3pi r^2 h is not the half of 4/3 pi r^3

toxic linden
#

what does this mean then:

toxic linden
faint pasture
#

they let the height = 2r

#

for almost no reason

#

and yea

#

its just a coincidence

#

if you want a proper proof of the volumes formulas thats gonna be #calculus

cunning lion
faint pasture
toxic linden
faint pasture
#

yall are lucky, i was introduced to calc for the first time in 10th grade and had to mostly self teach back then too

toxic linden
faint pasture
faint hollow
faint pasture
faint hollow
faint pasture
cunning lion
#

In today’s video we’ll make a little bit of mathematical history. I'll tell you about a major upgrade of one of Archimedes' greatest discoveries about the good old sphere that so far only a handful of mathematicians know about.

00:00 Intro to the baggage carousel
01:04 Archimedes baggage carousel
04:26 Inside-out animations
04:59 Inside-out di...

▶ Play video
marsh elk
#

Useless

queen coral
covert mango
#

i dont have

#

@queen coral

queen coral
#

Hm, ok

#

I liked this question

faint hollow
pearl compass
#

how do you solve this?

faint hollow
#

like length of first and last rod, spacing b/w holes

#

also it would help to take the bottom of first rod as origin

pearl compass
#

Alright, I will try that now. Thanks.

formal geyser
#

Hello

#

How do i solve this problem

vernal pilot
# formal geyser

This is really interesting. I would start by finding the side lengths of the triangle.

formal geyser
#

Of what triangle

formal geyser
#

I have found the rectangular

#

Both triangles have the area of 1 cm^2

formal geyser
#

These are the sides, since the side of the square is 2 cm

vernal pilot
# formal geyser

When it comes to geometry puzzles it helps to annotate as much as possible and remember you can draw lines as you want.

formal geyser
#

I have just solved it

#

4 cm^2

#

These are all the sides i have found

#

Then i calculated the area of upper small triangle (1/5 cm^2), added it to the 3 cm^2 of trapezoid (given in the instructions), calculated the area of the big square and substracted the are of trapezoid + triangle from it

#

The sides of the small triangle i have calculated using the similarity of triangles

#

The answer is right, but correct me if i overcomplicated the solution or did unnecessary steps

flint marlin
old haven
#

Sorry to bother you, I wanted to ask. I have the intention of joining the Mathematics Olympiad but I'm confused about where to practice. Do you have any suggestions for websites/YouTube channels for practicing math questions, guys?

undone quest
#

Grade ?

mild smelt
#

Website of the Olympiad? Problems from previous years

cunning lion
#

#competition-math may be more suited (see also the discord server in that channel's description)

gentle wren
#

yo how to do vector shit

#

im so confuse

#

like how to find the ratio of a point on a line doing vectors

round pulsar
#

Can someone give me a thorough explanation on how to do this please

cunning lion
#

use the pythagorean theorem

maiden brook
#

In triangle ABC, segment BD is an angle bisector of the triangle. suppose point E lies on AB. why does the reflection of E over BD have to lie on line BC?

formal geyser
#

hi

#

can anyone explain why if we have two triangle and all their corresponding angles are the same, then the triangles are similar and the ratio of their sides is the same? Is it because when the corresponding angles are the same, then the "shape" of triangles is the same while the size may differ

cunning lion
#

resizing a triangle doesn't affect the angles, so any two similar triangles can be thought of as the same triangle just moved around and enlarged/shrunk

#

and the size change affects all of the sides equally, so their ratios are preserved

formal geyser
#

okay, got it. By the way, the angles ratio doesn't equal the sides ratio?

#

@cunning lion

cunning lion
#

we have a theorem relating ratios of angles and sides which is the law of sines

formal geyser
#

i know it, just wanted to clarify whether it works with just angles

cunning lion
#

it does not

flint marlin
#

Could you verify your question?

faint pasture
faint pasture
flint marlin
#

Ok I didn't get the question then

faint pasture
#

Or nvm it isnt really coordinate

flint marlin
#

Could you explain the question?

faint pasture
#

Ah i need a diagram to explain the solution

faint pasture
#

Then i draw the angle bisector through A

#

Then the mirror image of B about the angle bisector

#

Will lie on AC

#

They just kinda changed it up a bit

#

Instead of B they took another point on the side

#

The solution doesnt change tho

faint pasture
#

They wanted to say BD where they said AB im kinda sure

flint marlin
#

Oh yeah

#

Got it

faint pasture
#

Reflection of a point about a line passing through it doesnt make sense and they defined BD

#

So ig yea they meant BD

flint marlin
#

Did you prove it?

#

Ok I got the proof nvm

faint pasture
# flint marlin Did you prove it?

I know the proof but i need a diagram to explain it properly and i dont have anything to draw it on

But basically let the side AB and angle ABC be fixed, ie all we can do to the triangle is adjust AC

So if we choose AC such that ABC is isoceless the mirror image of B will lie at C

However you can extend the side AC much as you want the mirror image wont change up

#

So we again fix up AC to be the original length

#

And the mirror image still lies on there

flint marlin
#

Hmm

#

Basically we can always find a point let say E such that AE=AB

#

On AC

faint pasture
#

Yea in short that

flint marlin
#

Yeah

#

Are you into olympiad geometry?

faint pasture
flint marlin
#

Oh..

faint pasture
#

I just had to do this proof for coordinate geometry

flint marlin
#

Oh

faint pasture
#

Which is in my syllabus

#

So yea

flint marlin
#

Mmmm

#

If you get any good questions , ping me please I would like to try

#

Because im preparing for the 2nd stage for representing my country in IMO , I just cleared the first stage

mild smelt
#

😊😊

formal geyser
#

Hi, how do i solve this one

#

I have already calculated the area of the left right triangle

#

But what about something that is similar to a circle's sector, but is not

#

I mean, the sector where "Blue Area" is written

#

I know it is not a part of a small circle, so i dont know how to calculate its area

mild smelt
#

Look at this triangle

formal geyser
# mild smelt

Okay, so it has 4 cm side and arctan(3) + 60° angle

formal geyser
mild smelt
#

Uhmm one of its angles is 30° actualy

formal geyser
mild smelt
#

So the red triangles angle is 30.. so now it's easy to find it's area...

maiden brook
#

so then how do u do it?

restive heron
#

Got a study question. I'm taking this trig course that doesn't have any lectures. It's basically read the chapter, then do homework problems. Then there's a huge playlist of trig videos. I don't know if this is normal for online school.

Anyways. Would it be more efficient to work on the problems as I'm reading? How do other folks study?

mild smelt
#

Everyone studies differently

#

But my personal approach is... go straight to the problems. and when you encounter some term your don't understand, find it in the lectures 🤣

restive heron
#

Lol. Thank you! I think I'm going to take this approach to the next section.

hot latch
#

can someone help

cold crane
#

does anyone know how to explain geometry proofs to me😔

hot latch
jolly hinge
#

help

#

😭😭

#

ive been on ts for 2 days😞

bitter granite
# jolly hinge

if you are allowed a calculator you could try an exponential regression

#

doubt it would work with only 2 points

#

yea idk then

hot latch
#

chat gpt it

trail tendon
jolly hinge
#

mb gng i turned ts in idgaf anymore😭😭😭

trail tendon
#

☠️

jolly hinge
#

yeah like i got notes from class but like i would keep applying it and it would say its wrong😭

trail tendon
#

br

hot latch
#

im struggling

trail tendon
hot latch
#

yes but i redrew it cuz she put the wrong degrees in hers

trail tendon
hot latch
#

she told us and i didnt wanna have to explain it so i just redid it

#

she put 60 instead of 45

trail tendon
#

oh

hot latch
#

do yk how to do it

trail tendon
#

i mean you know how a 45 45 90 triangle has side lengths 1:1:sqrt(2) where the hypotenuse is the sqrt(2)?

hot latch
#

yes

trail tendon
#

can you see that your diagram is a 45-45-90 triangle?

#

i mean the triangle created between the person on the boat and the tower

hot latch
#

oh so would i be like tan45=5280+x/1454

trail tendon
#

because the angle of elevation is 45 degrees, and the tower goes straight up

trail tendon
#

that works

hot latch
#

okay so im just slow

#

let me work it out

trail tendon
hot latch
#

i just didnt even consider that until you reminded me 45-45-90s exist

trail tendon
#

😂

hot latch
#

hold on theres another i cant figure out

#

if u dont mind

trail tendon
#

what is it?

hot latch
#

one sec

#

wait it doesnt work

#

tan45= 1 right

trail tendon
hot latch
#

so id be getting a negative if solving for 4

#

x*

trail tendon
#

uhhh

#

wait wth

hot latch
#

she somehow got this

trail tendon
trail tendon
hot latch
#

which if i used the 60 instead of 45 id have 1454 sqrt3

trail tendon
#

i guess the boat is on shore LOL

#

🤣

hot latch
#

imma DIE

#

hold on

trail tendon
#

that is actually very weird

trail tendon
# hot latch

is this from a textbook or did your teacher make this problem?

hot latch
#

she made it

trail tendon
#

💀

hot latch
#

but shes like hella smart so im lost

trail tendon
#

i think the answer is fine to be negative

#

logically it doesnt make sense but im not sure if she thought that through

#

like her answer is negative as well

hot latch
#

if she wouldve said 30 degrees it would make sense

trail tendon
#

i guess the boat is just on the shore 😂

hot latch
#

here lemme show u what she drew

trail tendon
#

ok

hot latch
trail tendon
#

XD

hot latch
#

im soooooooooooooooo lost lol

#

like that makes sense right??

#

where does she get the denominator 3

trail tendon
trail tendon
hot latch
#

her answer is 1454sqrt3/3 - 5280

#

so like

trail tendon
#

oh

hot latch
#

i have that but just no demon

#

denominator**

trail tendon
#

🤣

#

tan(30 deg) = sqrt(3)/3

#

tan(60 deg) = sqrt(3)

#

tan(45 deg) = 1

#

💀

hot latch
#

right thats exactly what im thinking

#

bro whatever hopefully i get partial credit for setting it up right

trail tendon
#

if you answer the question as is

hot latch
#

i mean if theres one similar on the test

trail tendon
#

correctly

hot latch
#

here this was the other one

#

thats the answer but coukd u explain why i use tan -1 cuz she never even showed us that

trail tendon
#

ok so tan(x) = 9.3/7.4, that makes sense right?

hot latch
#

YES

trail tendon
hot latch
#

sry caps

trail tendon
#

do you know inverse functions?

#

or like what they are?

hot latch
#

i mean isnt it cotangent

trail tendon
#

no, thats the reciprocal

hot latch
#

oh

trail tendon
#

of tangent

hot latch
#

i thought tan-1 was cot

trail tendon
#

nah they're different

#

tan^(-1) is arctangent

hot latch
#

okay so how do i know to use that?

trail tendon
#

or inverse tangent

#

basically, if you apply an inverse function to a function of x, you get x back

#

so arctan(tan(x)) = x

#

so, if tan(x) = 9.3/7.4, you can take the arctan of both sides
arctan(tan(x)) = arctan(9.3/7.4)
x = arctan(9.3/7.4)

#

does that make sense or 💀

trail tendon
#

because arctan(tan(45 degrees)) = arctan(1)
45 degrees = arctan(1)

hot latch
#

LMFAO wtf is an arctan is that just the inverse thing

#

bro 💀

#

im cooked

trail tendon
#

arctan(x) = tan^(-1)(x)

#

so if y = tan(x), x = arctan(y)

#

(theres domain restrictions but that doesnt matter for triangles here)

trail tendon
hot latch
#

okay so how do i know like when to use that? like when i am trying to find the angle of depression?

trail tendon
#

you want to know the angle

#

then you can use arctangent

#

x = arctan(something)

#

and then you can probably just plug into a calculator lol

hot latch
#

omg ur lying so tanX is tan^-1??

#

times whatever

#

so like tanX=(7.4/9.3) so i can do tan-1(7.4/9.3)

trail tendon
trail tendon
#

x = tan^(-1) (7.4/9.3)

#

and then you plug that into a calculator because no one in their sane mind would manually estimate that

hot latch
#

ohhhhhh i see omg okay i get it

hot latch
#

also i figured out the other one

#

no u right tho

#

those ppl scare me

trail tendon
#

oh cool

hot latch
#

i did adj/opp instead of opp/adj lol

#

whoops

trail tendon
#

oh LOL

#

and its still negative 😭

hot latch
#

dumb mistakes will be the death of me

trail tendon
#

😭

#

just blame the brain not functioning correctly at that moment 100%

hot latch
#

ive been mixing up cos and tan for like the past 2 days and its actually driving me insane

#

true not my fault

trail tendon
#

try to use brain more ✅

trail tendon
#

use brain more

hot latch
#

the practice makes me wanna die cuz i panic so much abt this stupid class

trail tendon
#

😂

trail tendon
hot latch
#

idk i like over practice and then blank out when its infront of me

trail tendon
#

yea honestly thats relatable XD

hot latch
#

whatever hopefully that doesnt happen tmrw cuz it caused me to fail my first one

trail tendon
hot latch
#

ill try my best thank u for the help ill probably be back

#

i say give it 5 min

faint hollow
trail tendon
oblique widget
#

@trail tendon

#

i dont really understand the pattern

#

the triangle similarities

trail tendon
oblique widget
#

i do see that yes

trail tendon
#

and if NPL is 90 degrees, NPM is 90 degrees as well...

#

right?

oblique widget
#

i mean like the order

#

of the letters

trail tendon
#

ohh

#

go from left to right

oblique widget
#

ok so if i go left to right

#

pln

trail tendon
#

so MNL means if you start at M, then go to N, then go to L

oblique widget
#

is similar to

#

mpn

soft vector
#

Does anyone have any trigonometry tips and tricks to help with memorizing values on the unit circle

oblique widget
#

oh i know how to get to MNL just NPL and MPN

trail tendon
oblique widget
#

becausae if i find NPL and MPN i could find MNL

soft vector
#

I have some holes in my understanding I feel like im so close 😭

oblique widget
#

i dont understand lowkey dont see the vision

trail tendon
#

if you have triangles LPN and NPM, the corresponding sides have to match up. so LN is the hypotenuse, just as NM is the hypotenuse. LP is the long side, just as NP is the long side. PN is the short side (of triangle LPN), just as PM is the short side (of triangle NPM)

trail tendon
oblique widget
#

LN is hupotenuse and MN is hypotenuyse

trail tendon
oblique widget
#

yeah i see the right angle for both triangles

#

that lowkey make sense

trail tendon
#

mhm

oblique widget
#

so if i start at the right angle

#

for example i said

#

triangle pln

#

it would be

#

npm?

trail tendon
# oblique widget triangle pln

PLN goes along the long side and then it goes along the hypotenuse
NPM goes along the long side and then it goes along the short side.

#

so those wouldn't correspond, right?

#

but if you went like PNM

#

then you go along the long side and then along the hypotenuse

#

so that would correspond to PLN

oblique widget
#

UHH

trail tendon
oblique widget
#

sorry would it be like

#

NMP

trail tendon
#

NMP goes along the hypotenuse and then the short side, right?

#

(i'm leaving out the last but technically then it goes along the long side because its a triangle)

oblique widget
#

it does the hypotenuse

#

NM is the hypotenuse

#

HOLD ON

#

TRIANGLE PLN

#

WOUD BE SIMILAR TO

#

NPM

#

DID I GET I

trail tendon
#

PLN would be congruent to PNM

#

they both go through the long side, then the hypotenuse, then the short side

oblique widget
#

NO 3HQW6

trail tendon
#

huh?

#

💀

oblique widget
#

let ,e function rq

#

i kinda see it

#

but

#

let me show you an example

trail tendon
#

mhm

oblique widget
#

so

#

if it was

#

PLN

#

wouldnt the second triangle start with N

trail tendon
#

where?

oblique widget
#

im talking about the example i sent earlier

#

because based on this example i js send triangle KPM is similar to MPL

#

and it starts with M

trail tendon
#

PLN -> goes from P to L, then L to N

oblique widget
#

since its the last letter of the first triangle

trail tendon
#

then N to P but just considering the first two constructions is enough to identify it

oblique widget
#

dont my similarity triangle has to start with P

#

it would be triangle PNM would it

trail tendon
oblique widget
#

hypotenuse to the right angle

trail tendon
#

so NLP would be going along the hypotenuse, and then going along the long side

trail tendon
trail tendon
#

so those wouldn't be the same

#

however, if you did like MNP

#

it goes from M to N , and then N to P
first it goes through the hypotenuse MN, then it goes through the long side NP

oblique widget
#

this is confusing

trail tendon
#

similar to how NLP goes through the hypotenuse NL, and then through the long side LP

trail tendon
#

i dont know the greatest technical terminology for it lol

#

im saying "goes through" i don't really know how ur supposed to say it

#

but like thats the order

oblique widget
#

so does NPL similiar to MNP

trail tendon
#

if you walked from N to L to P, you went along NLP
first you went along NL (the hypotenuse route) , then you went along LP (the long side route)

trail tendon
oblique widget
#

oh shoot yeah

#

but looking at triangle LPN the long side for it is LN

trail tendon
oblique widget
#

because angle LPN is a right angle

trail tendon
#

sorry uh

#

the hypotenuse is LN

#

the "long side" i was using was the longest side that wasnt the hypotenuse lol

oblique widget
#

oh

trail tendon
#

oh right its called a leg i think

#

long leg 💀

oblique widget
#

i thought hypotenuse are the longest side

trail tendon
#

my bad

oblique widget
#

😂

#

that was a little confusing

trail tendon
#

i was just calling it long side because it was longer than the short side and the hypotenuse was diffferent

trail tendon
oblique widget
#

so lets say PNL

#

it would be PMN?

trail tendon
oblique widget
#

NO

#

what

#

i was taught that the middle letter of a triangle is always a right angle

trail tendon
#

if you start at P, go to N, then go to L, you traverse the short leg and then you traverse the hypotenuse

oblique widget
trail tendon
#

if you start at P, go to M, then go to N, you traverse the short leg and then the hypotenuse

trail tendon
# oblique widget

you should probably add arrows i dont know which one was first 💀

trail tendon
#

if you're considering an angle, <PLM, then you are talking about <L

#

but theres no guarentee of a right angle and we're talking about triangle orientation and not the angles

oblique widget
#

uh oh

trail tendon
oblique widget
#

well this is my problem

trail tendon
#

yea

oblique widget
#

why are they flipped

trail tendon
oblique widget
#

back to this problem

#

my teacher took the first letter of the first triangle

#

and the last letter of the second triangle

#

then filled in the middle letter

#

i dont se that pattern for the answert i put

trail tendon
oblique widget
#

you see triangle KPM

#

the first letter is K

#

and the last letter of triangle KML is L

#

and for the middle letter you just fil in whats missing

trail tendon
#

oh i see

trail tendon
oblique widget
#

bruht

#

she literallyt said that

#

why is she giving me problem that ion know how to do

trail tendon
oblique widget
#

in general

trail tendon
#

💀

trail tendon
# oblique widget

did you go through these and you think the answer is D or you're not sure?

oblique widget
#

i have mp odea

#

no idea

trail tendon
#

ok

#

for LMN, first you go along LM, and then you go MN, does that make sense or nah?

#

like you go from L to M to N

#

if you start at L, then go to M, then go to N
its the same as starting at L, walking the distance of LM, then walking the distance of MN

oblique widget
#

i mean i get what you['re saying

trail tendon
#

so for LMN, first you walk the hypotenuse, then you walk the shortest leg, right?

#

it makes sense so far yes?

oblique widget
#

consider

#

ablly

#

next qauestion

trail tendon
oblique widget
#

i dont wanna spend too much time on one, i partially understood it but i need to move on

#

i still got a lot

trail tendon
oblique widget
#

well is it what is it

#

nextone

trail tendon
oblique widget
#

no i cant

#

i dont know ho

#

ww

trail tendon
#

:<

oblique widget
#

don t blame me my teacher dont teadch

#

im trying my best

trail tendon
#

do you know that the ratio sides of similar triangles are the same?

oblique widget
#

oh yes

#

i know that'

trail tendon
#

i just drew each triangle i saw within this triangle, and you can tell they are similar because of the angles

oblique widget
#

so how do i find the variables

lilac nebula
#

Can anyone figure out the longest pole that can fit through this corridor without using a calculator

hoary totem
lilac nebula
hoary totem
lilac nebula
hoary totem
#

good

#

so now look at this triangle

#

u know the angle and the opposite side

#

do u know any relation that can give you the length of the hypotenuse y?

hoary totem
#

oh ur wondering how to find the sine value without a calculator

hoary totem
#

generally this is impossible

#

unless u have a table of sines

#

which im guessing u dont

#

so if u dont have a calculator u can leave it as sin(37.5)

faint hollow
#

well sin(37 degree) is approximately equal to 3/5 or 0.6

faint hollow
graceful talon
#

,,\sin^{-1}\theta+\cos^{-1}\theta=\frac{\pi}{2}

somber coyoteBOT
lilac nebula
faint hollow
#

can you resend the question

#

or tag it maybe

lilac nebula
faint hollow
lilac nebula
faint hollow
#

yeah the answer seems to be correct, but i might have a way to prove it

#

i'll need some time to write it down

faint hollow
lilac nebula
lilac nebula
faint hollow
lilac nebula
faint hollow
#

what was your idea regarding the proof??

lilac nebula
pulsar prawn
faint hollow
marsh elk
#

Express an angle of 1.26c/rad in degrees & minutes.

Before converting the answer to degrees and minutes, is it 72.18 Degrees or 72.19?

worldly iron
#

hello

marsh elk
#

ridiculous

obsidian harness
#

,w 1.26 gradians / radians

obsidian harness
#

if the digit after the 8 is 5 or higher, round up, so 72.19

#

if it's 4 or below, round down, so 72.18

marsh elk
obsidian harness
#

why the heck are you so rude

marsh elk
#

rad

obsidian harness
marsh elk
obsidian harness
#

,w 1.26 * 180/pi

obsidian harness
#

it's not equal to 72.18 degrees or 72.19 degrees exactly

marsh elk
marsh elk
dense wren
#

"ok u are dumb, thanks"

narrow olive
#

How are they not banned yet

broken dock
broken dock
light dock
marsh elk
#

the discussion here tends to prioritize superficial intelligence focusing on surfacelevel interactions rather than engaging with the profound themes and complexities that this channel aims to explore

copper comet
#

homie if you cant understand the surface, good luck with the profound stuff

tough jolt
#

i got sniped

marsh elk
#

maybe I should come back in 5000yrs when intelligence has increased
ciao ciao ^^

dense wren
mighty dawn
obsidian harness
#

then you can set up simultaneous equations for both the big and the small triangles, in terms of both x and h

#

using tangent

mighty dawn
#

how do i set up the simultaneous equations with tan?

obsidian harness
#

so can you set up an equation like this for the triangle with 43 deg?

mighty dawn
#

tan(43) = 2?

flint marlin
#

Dont forget this

obsidian harness
#

what's the side opposite the 43 degree angle?

mighty dawn
#

h

obsidian harness
#

yep!

#

okay what's the side adjacent to 43 degrees?

#

so the adjacent side is not the opposite side, and it's also not the hypotenuse

mighty dawn
#

2

obsidian harness
#

cool

#

putting it all together

#

tan(43) = h/2

mighty dawn
#

for the other triangle would it be tan(31) = h/x

obsidian harness
#

draw the big triangle out

#

the adjacent side is not x

mighty dawn
#

is it not? it can't be O, would it be H?

obsidian harness
mighty dawn
#

x + 2?

obsidian harness
#

yep

mighty dawn
#

so tan(31) = h/x+2

obsidian harness
obsidian harness
#

now from tan(43) = h/2

you get 2 tan(43) = h

#

can you do something similar to tan(31) = h/(x + 2)? so that you get rid of the fraction?

mighty dawn
#

2x tan(31) = h ?

obsidian harness
#

you should get (x + 2) tan(31) = h

mighty dawn
#

oh ok

obsidian harness
#

and then you can combine 2 tan(43) = h and (x + 2) tan(31) = h !

#

||2 tan(43) = (x + 2) tan(31)
2 tan(43) = x tan(31) + 2 tan(31)
2 tan(43) - 2 tan(31) = x tan(31)
(2 tan(43) - 2 tan(31))/(tan(31)) = x||

jade sierra
#

quick

#

need help

#

i got 239.1 cuz the teacher taught us to subtract the quadrant degree with the one you get from doing tan^-1 (y/x)

cunning lion
#

if the x component is negative then you should add 180° to the angle

jade sierra
#

oh

#

💀

#

i thought you always subtracted

#

god this delta math took me a hour 30 to do prob

#

and i got a test on this in 2 days

gilded bronze
#

Finally finished this code, yall might find this very useful. Or not lmfao

flint marlin
high solar
#

can anyone help me?

#

i sent question in help

flint marlin
#

Send here

flint marlin
zealous pike
#

It is an exercise that got in my mind. Given the right triangle ABC, two triangles can be formed by drawing a line that bisects the right angle and intersects the point N, a line perpendicular to AB that intersects point N and a line perpendicular to AC that intersects point N. Show that the figure formed by the points AMNO is either a square or a rectangle.

#

Given that AMN is a triangle and that line AN bisects the angle BAC, the angles of the triangle AMN are 90, 45 and 45, because 180 = 90 + 45 + x.

That being the case, side AM is equal to side MN.

Angle NAO is equal to the angle MAN, AN is equal to AN, angle ANO is equal to angle ANM, therefore the triangle AMN is congruent to the trianglr ANO by ASA, hence, figure AMNO is a square

#

Is this right?

winter dagger
#

Hii I have a question abt trig:

#

if sin^-1 x = arcsin x rather than csc x, is sin^-2 = arcsin^2 or csc^2 x?

#

I know that trig function to the -1 makes it an inverse, but I was just wondering abt all other negative numbers

obsidian harness
somber coyoteBOT
obsidian harness
#

but it would be csc^2 x

unkempt gulch
#

I need help finding h.

obsidian harness
#

so you have h/x = tan 60

#

can you set up a similar equation for the 45 degree angle?

#

(in fact the 45 makes x really easy to figure out, since you have a right triangle haha)

kind rapids
somber coyoteBOT
#

҉C ҉l ҉ø ҉s ҉e ҉r

unkempt gulch
unkempt gulch
#

Ok

#

Thanks

obsidian harness
#

np

unkempt gulch
obsidian harness
#

tan(45) = 1

obsidian harness
#

so (x + 10)/x = sqrt(3)
x + 10 = sqrt(3) x
x - sqrt(3) x = -10
x = -10/(1 - sqrt(3))

#

and h = -10/(1 - sqrt(3)) + 10 so round that to the nearest m

unkempt gulch
winter dagger
obsidian harness
#

I mean $\sin^1 (x)$ looks weird

somber coyoteBOT
obsidian harness
#

but yeah apart from that, yes

old elbow
#

Does anyone know how to solve this problem?

formal geyser
# old elbow Does anyone know how to solve this problem?

The first one:
Minute hand rotates with 6° per minute (360°/60 minutes), hour hand rotates with 360/ degrees per second (24 hour is 1440 minutes). So we need to determine the time when two hands meet each other, so the angle between 12:00 and the minute hand equals the angle between 12:00 and the hour hand. X is this time.
x * 6 = 150 + x*360/1440. The answer is x equals 26 minutes and around 5 seconds

#

05:26:05

hard smelt
#

I was following along until it says divide the interval between the two vertical asymptotes. Where on earth are they getting those numbers from?

cunning lion
#

the length of the interval is (pi/2 - 0) = pi/2

#

each subinterval should have 1/4 of that length

#

therefore each subinterval should have length (1/4)*(pi/2)

hard smelt
cunning lion
#

if you want to divide something into 4 equal parts, mathematically that corresponds to dividing by 4

hard smelt
deft sail
#

Do you have to know Half/Double angle formulas

#

Or do you not have to and do something else

#

They do feel stupid to me

cunning lion
#

the double angle identities are special case of the angle addition identities

#

and the half angle identities are a rearrangement of the double angle identity for cosine

trail tendon
limber phoenix
#

Can omeoe help me

#

HOW DO I FIND THE LINE OF REFLECTION

wheat granite
limber phoenix
#

Its this

#

I understand that the line of symmetry has y

#

But Im not sure if its y=0 or y=-r

wheat granite
#

its y=0

#

the midpoint between n and -n is 0

limber phoenix
#

Okay thank you so much

limber phoenix
#

?

#

It was y=-r

#

I got it wrong

#

THanks anyway

wheat granite
wheat granite
#

If I somehow end up with a situation like this in a two-collumn proof, what reason can I give for angles a and 1 being congruent? (the white lines are the same)

cunning lion
#

sin(2a) = sin(a+a)

uncut portal
#

Is this where you can get help?

#

Wait this isn’t a geometry nvm

runic scarab
#

idk if this is the right place to ask about 3d transformations, but heres my question:
assume you have a point P at (1 ,3, 1)
you want to scale it by 2, rotate about the y axis by 45 deg and the x axis by 30 deg, then you to want to transalte it by (2, 0, -1)

warm shuttle
#

that's not a question

runic scarab
#

forget to mention "where will that point be?"

formal geyser
warm shuttle
#

p and q are +1 or -1 depending on the direction of each rotation

runic scarab
#

oh mb, i apologise 😅 but how have u done this? i was looking at one of the given slides and they have done this

warm shuttle
#

oh with homogeneous coords you just google what the correct matrix for each transformation is and then let computer do its thing

runic scarab
#

whhatt, how? i have a online (open book) test on this soon

warm shuttle
#

which part do you not understand?

#

you form your vector with your x, y, z and w = 1 (pretty sure, double check with the book)

#

then you figure out what the matrix for each transformation is

#

again double check with book or online resources

#

then you apply them in order

#

reading from right to left

#

S - scaling
R_2 - rotate
R_1 - rotate
T - translate

runic scarab
#

um so i understand that the order of caluations go this way but what i dont understand is why the second rotation is calcauted before the first and both the rotaton stuff is inverted

warm shuttle
#

i think that's just a naming thing

runic scarab
#

hm?

warm shuttle
#

R_2 applies before R_1

#

it seems to say something about inverses

#

which you left out

#

but if you wanna do like f(g(x))

#

and then you want to get back to x you do g^-1(f^-1(f(g(x))))

#

so that you cancel them out

#

so if you are undoing transformations then the naming makes sense

#

otherwise it's weird

runic scarab
dense smelt
#

How is this a parallelogram in the first place?

#

If I got the props of parallelogram right, then it doesn’t make sense bc equilateral triangle but 8 , 6?

hard smelt
#

how am I supposed to figure this out? I don't have a cot function on my ti84 and even if I did it would give it to me as a decimal

mild smelt
#

Remember the definition of cot

ivory cloak
#

Aider moi s'il vous plaît

deft sail
ivory cloak
#

Merci infiniment

deft sail
#

Je suis vraiment confus sur cette question ? Je ne l'ai tout simplement pas fait depuis un moment. Je ne sais pas ce que je suis censé faire

mild smelt
#

Reflect one of the points over the line. Shortest path is a straight line.

#

So angles should be equal

upper karma
#

.

#

Consider an n-sided polygon.
What is to be found is the number of in it.

Let the first point be A.
We move Anti-clockwise.
From point A, the number of diagonals (on observation) = n-3 (in which we excluded from A to U - the last point and B - the adjacent point).

#

For this (from point B) there are n-3 diagonals again (without any re-ocurrence of any diagonal).

#

Things become a little sus for point C.

deft sail
#

I never learned this yet 😭

upper karma
#

This is not a subject to be learnt; it's logic.

deft sail
#

I don’t use logic that much

upper karma
#

No problem.

deft sail
#

Oh it actually makes sense

#

I never thought of reflecting the point

#

I thought it was already equal by four parts

upper karma
#

Now for point D there are two re-occurrences.

#

AD and AB.

#

So we subtract two.

#

We get (n-3) - 2 diagonals.

deft sail
#

😼👍

upper karma
#

Let the last two points be P_(n-1) and P_(n-2).
We can find the number of diagonals (without coincidence) for S (because for T and U all diagonals will be repeated).
For C which was the P_3 point, there were (n-3) - (3-2) diagonals.
On observing we can generalize this for a give point P_k (considering first point as A).
Number of non-repeated diagonals from P_k in this polygon of n sides = (n-3) - (k-2) = n - 3 - k + 2 = n-k-1
Tada!
S is the P_(n-2) point.
Observing the pattern we get it has (n-3) - (n-2-2) diagonals which equals n-3 - n + 2 + 2 = 1 diagonal.
The number of points (including S and C) between S and C = n-4.

In conclusion the total number of diagonals can be given as follows:
(n-3)(n-2) - (n-4)(n-3)/2 = n(n-3)/2

Here's the breakdown of each part:

For the 'without subtraction' part for the diagonals for a given point we have n-3.
Now it continues till S [which is (n-2)].
So we multiply (n-3) and n-2 to get (n-3)(n-2).

The subtraction part continues till S (from C).
So we subtract the summation of the natural numbers from k = 1 to k = n-4 (since the number of diagonals to be subtracted for the n-2 point = n-(n-2) - 1 = n + 2 - 1 = 1.
And the difference between the location, aka the number (for example, 1, 2, 3...., etc.) and the second part of the term (n-k) where n-k = the subtraction to be made for the point n-k+2.
_So that thing for S is (n-4).
_So finally the thing that we have to subtract = the summation of natural numbers from 1 to n-4 = (n-4)(n-3)/2.

#

The final formula for this calculation becomes:
(n-3)(n-2) - (n-4)(n-3)/2
= (n-3)[(n-2) - (n-4)/2]
= (n-3)[{2(n-2) - (n-4)}/2]
= (n-3)(n)/2
Which is the required formula.

#

So the question I am asking is:
Are all the steps of my monumental proof correct?
I know that all of it is correct but I would like to hear praise from others.

zealous pike
#

Can someone help me please

#

Well

#

It is a question that came from my mind

#

Given a conic section of height h and radios r, what function describes the change of r as h grows or decreases?

flint marlin
#

But I would prefer combinatorics here

mild smelt
#

Hmm.. there are n points and each point can be connected to n-3 other points by a diagonal.

n(n-3) will be each diagonal counted twice, so to get the answer just divide by 2

n(n-3)/2

upper karma
#

how

upper karma
#

nC2 - n

split charm
upper karma
#

in this figure where all the diagonals are joined of a 21-sided regular polygon, how many triangles have been formed in total (every triangle)

#

inside the polygon, as small as a bacteria and also including triangle formed by the vertices of the polygon

mild smelt
upper karma
#

i am just one ahead of them

#

can anyone calculate this for me

#

for number of sides = 21

zealous pike
#

sully i am invisible

wise zodiac
#

does anyone know how to prove the ares of XYW = ZYW USING HERONS

obsidian harness
#

just note that the perpendicular height of W above XY and YZ is the same

wise zodiac
obsidian harness
#

if you insist

wise zodiac
#

but i want to do it with heron's because i'm learning what's going wrong

#

😭

#

can u help me

wise zodiac
obsidian harness
# wise zodiac

use the fact that cos(x) = -cos(180 deg - x) and then cosine rule, that might work

wise zodiac
#

wouldn't that give negative measure lol

obsidian harness
#

$\frac{XY^2 + YW^2 - XW^2}{2 \cdot XY \cdot YW} = -\frac{YZ^2 + YW^2 - WZ^2}{2 \cdot YZ \cdot YW}$

somber coyoteBOT
wise zodiac
#

nice thing is using that argument you can have sin(x) = sin(180 - x) and yet another proof to show that the area is equal

obsidian harness
wise zodiac
#

i think u got it 😭

obsidian harness
#

basically if we have a way to relate XW and WZ somehow

#

$XY^2 + YW^2 - XW^2 + YZ^2 + YW^2 - WZ^2 = 0$

$2 XY^2 + 2 YW^2 - (XW^2 + WZ^2) = 0$

somber coyoteBOT
wise zodiac
#

so it's just not sufficient right?

#

sufficient information*

obsidian harness
#

it's going to be hell algebraically

#

I think it will work somehow but don't ask me

wise zodiac
#

u mean it's possible?

obsidian harness
#

ye

wise zodiac
#

wow

obsidian harness
#

then I think this form would be the most useful

#

so if we let a = XY and b = YW
and a' = YZ and b' = YW for the other triangle

#

we just need to consider a^2 + b^2 - c^2

obsidian harness
somber coyoteBOT
obsidian harness
#

so $(XY^2 + YW^2 - XW)^2 = (XY^2 + YW^2 - ZW^2)^2 = (YZ^2 + YW^2 - ZW)^2$ hence proven

somber coyoteBOT
wise zodiac
#

@nocturne remnant (sorry for ping) helped me solve it

#

😭

obsidian harness
#

nw

zealous pike
#

Is it possible to use the similarity of triangles to find the height of the smaller conic section?

#

I thought about something like this

#

The height of the small conic section is 12

tame oriole
#

guys what do i need to know to learn trigonometry

mild smelt
#

Everything that is in your geometry textbook before trigonometry 🤔

zealous pike
#

Anyway

zealous pike
maiden brook
kind quail
#

Hello I have this in my home work which is just really practice questions. And I can not seem to figure out exactly how to solve this using sine

#

I've been trying but nothing seems to add up

acoustic pollen
spark vale
#

How can I find the answer of tan(135) ?

#

let's say I don't know how to find the answer of trigonometry functions when the theta value is over 90 degrees.

kind quail
spark vale
#

i know how to solve it.
tan(135) = -tan(45)

#

but this does not make sense

acoustic pollen
spark vale
#

but how can we find the answer with 45 degrees for that?

#

nonsense to me

acoustic pollen
spark vale
#

yes

#

that's what i am using

#

the radius is 1. that's unit circle

maiden brook
acoustic pollen
#

i mean not fully equal since one of them is negative

spark vale
#

but what's that tangent line

acoustic pollen
#

tan axis

spark vale
#

i am not finding any relationship between Tan func and that line

acoustic pollen
#

ok so in the unit circle, the y axis represents the sine and the x axis the cossine, right?

spark vale
#

yes

#

because the radius is 1

acoustic pollen
#

all the other trigonometric functions like tan, csc and cot also do have lines that represent them

#

that one is for tan

spark vale
#

really?

#

this is the first time i hear

#

now i think i need to understand why they have those lines.

#

I will show u what i am thinking of trigonometry funcs

spark vale
acoustic pollen
#

but the one i sent you is a way to visualize it

spark vale
#

so u see there's no extra line on the image

#

only triangle inside the unit circle.

acoustic pollen
#

yeah because usually you don't need it, but that doesn't mean it's not there

#

wait let me try to find an image of the full unit circle

spark vale
#

thanks