#geometry-and-trigonometry

1 messages Ā· Page 73 of 1

signal field
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ok one sec im getting the screenshot

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this is central arcs and angles my question is when would i use 2pir

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i understand the formula theta/360=S/C

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but i dont understand when would i use s/2pir=theta/360

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this textbook im reading from doesnt really explain it well

kind rapids
signal field
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yea

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circumference/diameter

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=2pr?

kind rapids
somber coyoteBOT
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Closer

signal field
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ok circumference =2pir

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@kind rapids if i was to just say s/2pir for the first example would that be wrong?

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instead of s/c

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since c= 2pir

kind rapids
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But you are trying to compute circumference

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So no need to make it to 2pi r

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But if you need to compute r then you need to write it as 2pi r

signal field
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ok so when i need to find radius use 2pir

kind rapids
somber coyoteBOT
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Closer

kind rapids
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And then find r aka radius

signal field
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ok thank you!

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ima have to get a on-campus tutor asap because its only been a week and im alr lost

oblique widget
void ivy
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why is the answer 20? i was thinking 10

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this is the answer but isn't that the just the whole area of the flag

north kindle
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are we assuming the flag is a rectangle?

void ivy
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sorry, triangle

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the topic is about triangles

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but now that you've mentioned it, it may be a rectangular flag, where the diagonal divides it into 2 triangles, which one is of area 20in^2

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thanks šŸ‘

faint pasture
void ivy
void ivy
# faint pasture Well thatd be an altitude

oh does it? hoepfully i get to that part soon, on the book i'm reading. i'm relearning math from the absolute basics to build a solid foundation before i move to more advanced topics like chemistry, physics, pre-calculus, and hopefully i'll understand calculus intuitively one day 🤣

faint pasture
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Calc isnt as tough as an high school tchr/ the society makes it out to be anyways

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Its rather doable

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Good luck though

azure helm
maiden brook
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what’s angle EAD

mellow quest
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$\angle BAD= \angle BAE + \angle EAD \
90 = \angle BAE + 60$

somber coyoteBOT
#

olivka

maiden brook
mellow quest
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150

onyx tiger
tepid axle
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what does it mean when a function is defined for all R and how do i explain it?

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i have two functions, f(x) and g(x) where h(x) = f(g(x)). f(x) and g(x) are both defined for all R

faint pasture
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Then h(x) is defined for all R

tepid axle
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yes my teacher said i didnt explain it right

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and he wants me to explain more lol

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he gave me a tip and wrote "is h(x) definition dependent on definition for f" - sry direct translation

upper karma
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wdym

tepid axle
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so he asked me if h domain is dependent on f domain since h(x) = f(g(x)). As both f and g are defined for all R. cause i just wrote h is defined for all R

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$h(x)=-\frac{3\sin(\pi*\frac{3x}{2})}{4}-1$

somber coyoteBOT
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delila

pearl bolt
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Prove Sin^2 + cos^2 = 1 please help me out..

obsidian harness
pearl bolt
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What defination?

obsidian harness
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normally we define cos to the the x-coordinate of the unit circle and sin to be the y-coordinate

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so applying the Pythagorean theorem directly, cos^2 + sin^2 = 1

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1^2 = 1

pearl bolt
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But image is wrong

obsidian harness
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howso

pearl bolt
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cos should me in sin's place and sin should be in cos's place

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@obsidian harness

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And can you explain the image please

obsidian harness
obsidian harness
pearl bolt
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But how can we use pythagoreas here

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I am 10th not something like university level

obsidian harness
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cos is the x-axis

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sin is parallel to the y-axis

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x- and y-axes are perpendicular

pearl bolt
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And you get hypotenus which is 1

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But how can it be 1

obsidian harness
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yeah we define it to be the unit circle, so we start out with the circle x^2 + y^2 = 1^2

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and then draw cos and sin on the unit circle

pearl bolt
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Thank you very much mann

faint pasture
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P²+ b² = h²

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And divide by h²

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Tho this only works for right triangles

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But eh in 10th grade thats prolly all youre gonna have to deal with

obsidian harness
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npnp

obsidian harness
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by Pythagoras

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I'm just introducing the unit circle cause things become simpler if we just let the hypotenuse be 1

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and it's useful to do your trig in all 4 quadrants

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rather than having to memorise CAST

faint pasture
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But like idk if they were introduced to trig the unit circle way in schl

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Cuz for me it was all triangles

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So yea

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I mean yes unit circle is objectively better

obsidian harness
faint pasture
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But yea

obsidian harness
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like say for any triangle we can use SOHCAHTOA, but by similarity we can let hyp = 1

faint pasture
obsidian harness
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cause trig ratios aren't affected in similar shapes

faint pasture
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So circle should be prioritised

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But yea the ed system sucks here

kind rapids
faint pasture
faint pasture
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But the unit circle came like an year later after the triangle shit

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So yea

upper karma
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but unit circle is just good

faint pasture
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Yea its better objectively

upper karma
#

i was happy to visualize trig with unit circle

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when i was taught trig

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than i was with triangles

tepid axle
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whats the difference between range and codomain? i wrote two different things on them but still got wrong 😦

tepid axle
#

oh my teacher replied and said that they in general dont have to be the same? 🫣

obsidian harness
#

the range, which you should refer to as the image, is a subset of the codomain

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for example, if I have $y = x^2$ where $x, y \in \mathbb R$

somber coyoteBOT
obsidian harness
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the codomain is R

tepid axle
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yeah

obsidian harness
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but the range is just f(x) >= 0

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fixed the typo sorry

tepid axle
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question

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so is

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[-1, 1] range then?

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he said i had written basically the same on both

obsidian harness
tepid axle
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sin

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just example xd

obsidian harness
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oh

obsidian harness
tepid axle
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yeah the range for the above one is smtn else

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ohh ok idk he just wrote i had done the same on both

obsidian harness
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yeah the codomain can be defined as anything, although a natural choice for the codomain is all real numbers

tepid axle
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cause i had defined the function for all R and then for range i wrote tht

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yeah

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this is the range for the function above

obsidian harness
#

to properly define a function you need 3 things:

  1. the domain
  2. the codomain
  3. the relation between the domain and codomain, the function 'rule'
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at high school level we assume that 1) and 2) are all real numbers unless specified otherwise

tepid axle
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ye

obsidian harness
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not many high schools teach Diophantine equations

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those are the solutions to ax + by = c if x, y are now integers

tepid axle
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ohh i see

obsidian harness
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so yeah 1) and 2) are important, just make a mental note of that

tepid axle
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thanks so much

obsidian harness
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np

tepid axle
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if u have time otherwise its ok

obsidian harness
pearl bolt
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Why should we consider hypo as its answer as 1?

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Please help out with this

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<@&286206848099549185>

trail tendon
tepid axle
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to prove a function is surjective do i do f(x) = y?

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and then calculate it?

midnight merlin
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does anyone know the actual name of a cubic Torus(ring shape)??? im going crazy as it does not have a name

azure helm
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help

thorn dune
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Maybe 30?

azure helm
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explain

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AED and abcd are coplanar

lyric sonnet
lyric sonnet
azure helm
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yeah

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it's 2d

maiden brook
azure helm
azure helm
azure helm
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I figured it out

azure helm
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help

north kindle
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whats another way to express DAE

azure helm
atomic copper
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do i need to memorize trigonometric identities or can i just figure them out during my test

light hemlock
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Hello, could anyone explain to me how I’m supposed to solve number 15. I already tried a few things but I’m getting the wrong answer still.

warm shuttle
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you have b/c = sin(β)

azure helm
obsidian harness
azure helm
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how so?

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can u make a drowing

obsidian harness
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If M is the midpoint of DE, we want DM and AM

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Let DM = 1 so the height of the square is 2

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Then the height of the triangle will be sqrt3

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So that arctan is angle DAM and we multiply it by 2

oblique widget
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Can somebody help

fallow palm
warm shuttle
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,w 2d distance formula

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$\operatorname{dist}(a, b) = \sqrt{(x_a - x_b)^2 + (y_a - y_b)^2}$

somber coyoteBOT
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CyclicTree

warm shuttle
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this 4 times (or 2 if you are lazy) gives perimeter

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,w gauss shoelace formula

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$2A = (x_1 y_2 - x_2 y_1) + (x_2 y_3 - x_3 y_2) + \ldots + (x_n y_1 - y_n x_1)$

somber coyoteBOT
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CyclicTree

warm shuttle
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gives area

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or you can find the height. or you can also use law of cosines or cross product or determinant or whatever else

obsidian harness
azure helm
obsidian harness
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there has to be a simpler solution than using trig

azure helm
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okay

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geo is tricky

obsidian harness
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CD = CB = CA cause ABC is equilateral, so triangle CDA is isosceles

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so angle CAD = (180 - 90 - 60)/2 = 15

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by symmetry, angle EAB = 15

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so angle CAD + angle DAE + angle EAB = 60 and hence 15 + angle DAE + 15 = 60

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DAE = 30

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ok

azure helm
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can you show in a drawing

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i doont really get it

obsidian harness
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why don't you try drawing it yourself

azure helm
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i am having a bit of trouble with that

obsidian harness
azure helm
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everything I dont get it

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you went too fast

obsidian harness
azure helm
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if you can go slower that would be fine

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no sorry im am not

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I just wanted you to help me a bit with the drawing thats it

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is that fine for you, then I would nmot disturb you any longer

obsidian harness
azure helm
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how did u

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do that

obsidian harness
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I guess what I wrote isn't sinking in for you

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and I don't think me speaking more will help

oblique widget
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I found the perimeter but not the area

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I used the distance formula

warm shuttle
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Here's an idea

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You see how the x axis splits it into two triangles?

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Since parallelograms have opposite sides equal, you can cut off top triangle and move its long side to match the long side of the bottom triangle

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but then you still have the slanted bit on the right

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which you can again cut off and move to the left

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now you have a 5x17 rectangle

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so the area is 5*17

upper karma
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In geometry, an inscribed planar shape or solid is one that is enclosed by and "fits snugly" inside another geometric shape or solid. To say that "figure F is inscribed in figure G" means precisely the same thing as "figure G is circumscribed about figure F". A circle or ellipse inscribed in a convex polygon (or a sphere or ellipsoid inscribed i...

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According to conventions then is it alright to call a circle ā€œinscribedā€ in a rectangle?

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cuz it doesn’t touch all its edge and can at most touch 3

faint pasture
upper karma
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i mean yes obviously

faint pasture
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A square is just a special kind of rectangle

upper karma
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either 2 or at most 3

faint pasture
upper karma
#

if it’s a square then 4

faint pasture
upper karma
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and whether it allows shapes like this which isn’t ā€œtangentā€ to all sides

faint pasture
upper karma
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where in the wiki does it say that

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because i think this has to do with definitions

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and conventions

faint pasture
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Iguess so

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But idk how this will extend to circles

upper karma
#

i need a definitive answer on what the convention is

faint pasture
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I mean this kinda means that?

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But what even is a vertex in the case of a circle

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Tho there definitely doesnt lie one on the 4th side

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So yea

upper karma
#

that’s talking about inscribing a polygon in a circle

faint pasture
upper karma
#

check the sentence before that

faint pasture
upper karma
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no

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A circle or ellipse inscribed in a convex polygon (or a sphere or ellipsoid inscribed in a convex polyhedron) is tangent to every side or face of the outer figure (but see Inscribed sphere for semantic variants).

faint pasture
upper karma
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this sentence answers it

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you’re looking at the next

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which is the ā€œoppositeā€

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as in, it’s circumscribed now not inscribed

faint pasture
azure helm
faint pasture
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And ACD and ABE (the two new triangles) are isoceless

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Soo BAE = BEA

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And we also know ABE =ABC+CBE =90+60 =150

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So now you can find BAE and CAD

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Also CAB = 60 = CAD +DAE + BAE

outer wadi
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what does the second point mean

faint pasture
outer wadi
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oh so basically circle inside triangle touches point F,E,D

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?

upper karma
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the circle is tangent to each side yeah

outer wadi
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thanks

upper karma
# azure helm

ender already provided u a solution, but if u wanted another one:

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if you can show <CAN = <BAK = 15 then you're done

warm shuttle
azure helm
warm shuttle
azure helm
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help

pearl bolt
#

Prove sec

warm shuttle
# azure helm help

DCB = 90°, BCA = 60° -> DCA = 150°.
CB = DC, CB = CA -> CD = CA -> CDA = CAD.
DCA + CDA + CAD = 180°, CDA = CAD -> DCA + 2CAD = 180°.
DCA = 150°, DCA + 2CAD = 180° -> 150° + 2CAD = 180° -> 2CAD = 30° -> CAD = 15°.
Symmetrically, BAE = 15°.
ABC - equilateral -> CAB = 60°.
CAD + DAE + EAB = CAB, CAB = 60°, CAD = BAE = 15° -> 15° + DAE + 15° = 60° -> DAE = 30°

pearl bolt
#

Prove sec^2 = 1+ tan^2

warm shuttle
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what's sec?

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sec(x) = 1/cos(x)
sec²(x) = 1/cos²(x)

tan(x) = sin(x)/cos(x)
1+tan²(x) = 1 + sin²(x)/cos²(x) = cos²(x)/cos²(x) + sin²(x)/cos²(x) = (cos²(x) + sin²(x))/cos²(x) = 1/cos²(x)

upper karma
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they’re similar triangles

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also C(red) = B(red)

wraith hill
#

can somebody please help me with trigonometry?

obsidian harness
# wraith hill

problem 1: recall that a 45-45-90 triangle has sides 1 : 1 : sqrt(2)

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so what must you have to get ? : ? : x, if the hypotenuse is x

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once you figure out what ? is, ? + x + ? = 2 so you have an equation in x you can solve

warm shuttle
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for problem 2 you can consider triangle formed by centers of 3 smaller circles

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and then find the distance from its center to one of the vertices

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that +a gives you radius of the bigger circle

obsidian harness
#

it's the same deal with problem 2

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the middle triangle is equilateral cause all the sides have length 2a

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so you can use trig to figure out what ?, the distance to the centre of the big circle and the centre of the equilateral triangle, must be

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sine rule for example

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or right angled trig

wraith hill
obsidian harness
wraith hill
#

I didn't really get the terms you used to represent it

wraith hill
#

can I also ask how to get the sides of the triangle with only angles?

obsidian harness
#

so x cos 45 or x sin 45 would both work

wraith hill
#

ok thanks

tepid axle
#

if my function is supposedly surjective, the codomain and range is the same?

spiral widget
#

Yes

tepid axle
#

$[-\frac{7}{4}, -\frac{1}{4}]$ so this is codomain and range?

somber coyoteBOT
#

delila

spiral widget
#

For what function

tepid axle
#

$h(x)=-\frac{3\sin(\pi*\frac{3x}{2})}{4}-1$

somber coyoteBOT
#

delila

tepid axle
#

where h(x) = f(g(x))

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f is defined for all R and g R to R

spiral widget
tepid axle
#

ya

spiral widget
#

The codomain would normally be part of the data of the function

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In this case it could be any set containing the range

tepid axle
#

oh how do i

spiral widget
#

So, the codomain would normal be given to you, and it’s not really something you can deduce from just a formula

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The range/image is, though, so long as you know the domain

tepid axle
#

yeah

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my teacher said i got the codomain right but explanation wrong

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for why domain is R and codomain

lilac nebula
#

can anyone help me to find that angle??

faint hollow
#

DAO is coming out to be 80 ig and DEC is 60

lilac nebula
pearl bolt
#

Solve x^2 + x + 1

trail tendon
#

theres nothing to solve ._.

pearl bolt
#

There is find roots

warm shuttle
#

,w x^2 + x + 1 find roots

faint pasture
north kindle
#

im having trouble with this problem, i cant find any remotely nice expression for this line

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i got y = -x(2ca/(-2b + a))/a + 2ca/(-2b + a) but i feel like theres a better one

faint pasture
oblique widget
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The top one

spiral lodge
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Can you send a full picture?

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Btw, is that a test you're doing right now?

trail tendon
# oblique widget

it seems that you already did this, but you can use the fact that any two sides added up should be greater than the third side

spiral lodge
#

I thought it was a question on Pythagora's theorem

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Even though the 90° angle isn' marked with the usual little square šŸ¤”

oblique widget
trail tendon
#

where are you stuck šŸ’€

oblique widget
#

What’s the next step

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I have to write it as an inequality

signal field
#

How could I find an acute angle theta if it’s arcsin or arccos

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Problem 33

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Nvm I got it

steady vault
#

lol

blazing veldt
#

If $\cot \theta =- \frac{7}{2}$ and $\cos \theta > 0$, is $\tan \theta= -\frac{2}{7}$?

somber coyoteBOT
#

Primordial

twin spindle
#

Hello, im doing hw on Trig equations, and im confused on how to get multiple solutions, I was able to figure out 1 solution to this problem, but not for the other ones

upper karma
#

would point H be considered coplanar and why

faint hollow
faint hollow
warm shuttle
#

If the question is as you stated, then the answer is "no, because you can't talk about an individual point being coplanar"

opal sierra
#

Can someone teach me trig

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In dm

scenic field
#

Hi

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Pls i need help

#

Dm ne

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Me*

dawn scaffold
#

i too require further assistance in this subject

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nvm i got it guys :DD

faint pasture
#

(Find slope of the tangents then use that to find to slope of the normal and we also know the point)

faint comet
#

Guys, for question B does the domain after being manipulated become -10pi/3,x,8pi/3. I multiplied by 3 first then minused pi/3

graceful talon
#

Nani

zealous rapids
#

you manipulate the interval domain

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-3pi <= 3x <= 3pi

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so -10pi/3 <= 3x-pi/3 <= 8pi/3

faint comet
#

Can you find where u went wrong here

faint hollow
#

its hard to check this, but you can do one thing, just apply the general solution of cos Īø which is --> Īø = 2nĻ€ ± α, where α ∈ (0, Ļ€], here is alpha is any solution in the given range(for example in your case alpha would be Ļ€/3) and n is set of integers, from this you can easily put values of n that gives you the values in [-10Ļ€/3, 8Ļ€/3]

#

then solve for x

dawn carbon
#

tips how to study basic trig fast im in alg2 and have a math comp with it soon

twin spindle
#

When converting from rectangular to polar, how do you know whether you should add 2pi, add pi, or not add anything at all? Because on some of these answers it tells you to only do one of them or either

obsidian harness
#

so (-2, 1) is in the 2nd quadrant, so it would be pi - arctan(1/2) which is equivalent

#

the rule for arctan is that it always gives you an angle in the 1st or 4th quadrant

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1st quadrant gives you a positive angle and 4th quadrant gives you a negative angle

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so for the 3rd quadrant, add pi radians

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for the 2nd quadrant, also add pi radians

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for the 4th quadrant, you want the same position but you want to make it positive, so you add 2pi

obsidian harness
twin spindle
#

Alrr so basically we'd add pi or 2 pi, to find the other solution? And i'm guessing that the 2nd question didn't need to be added. because it's already in a positive coordinate?

obsidian harness
twin spindle
#

What's wrong with having negative values tho?

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I get if you were measuring something you don't want a negative value, cause that jus makes no sense.

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But in a case like this, why change it to a positive, if you got sum from the 4th quadrant?

obsidian harness
somber coyoteBOT
obsidian harness
#

that's the domain we usually use for angles

twin spindle
#

OHHHHHH

#

Omfg I can't believe I missed that 😭

#

That shi always gets me, whenever their's an interval

obsidian harness
#

*there's

twin spindle
#

Thank you for helping tho šŸ™

obsidian harness
pearl bolt
#

Prove that sec^2 = 1+ tan^2 through circle method

#

Please help me to prove this

next dome
#

@everyone@here

  1. Guys can anyone pls tell me that what is an arc in geometry?
  2. Guys can anyone pls tell me that what is pi maths?
modest mesa
#

i need help with this

stable ridge
#

3sinA+5cosB=3
3cosA+5sinB=7
Find cot(a+b)
Pls help
I got Final exam tomorrow

obsidian harness
#

now divide everything by cos^2

obsidian harness
#

also you can Google the answers to your 2 questions

obsidian harness
somber coyoteBOT
obsidian harness
#

square both of your simultaneous equations and add them together

you get $9 + 25 + 30 \sin a \cos b + 30 \cos a \sin b = 3^2 + 7^2 = 58$

somber coyoteBOT
obsidian harness
#

so use the Pythagorean identity to find cos(a + b)

#

great, now you have tan(a + b), then take the reciprocal of what you have to get cot(a + b)

obsidian harness
#

you should know how to express sin theta and cos theta in terms of tan theta at this stage

modest mesa
#

but ig i did it?

twin spindle
#

Is it okay if someone checks my answers on this review paper?

#

The problem is that, I jus wrote my answers and did the work on paper

agile cave
#

Help

hot latch
#

can someone pls explain this work

#

please

tall coral
hot latch
#

how did she get the y value

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and im just not seeing all the steps

tall coral
#

ok

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the first step is listing the equivelences based on what tan is

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then, they solve both equations for y

hot latch
#

so she just left off the "y="?

tall coral
#

yes

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because if they're both y, they equal eachother

#

think you got it?

hot latch
#

so she set the both equal to eachother and simplified

tall coral
#

yep!

#

then plugged the x value into the original equation and solved for y

hot latch
#

where did the x in the right half of the equation go

#

oh

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thats why its minus

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no

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idk

tall coral
#

$x \tan(63)- x \tan (53) \rightarrow x(\tan(63) - \tan (53))$

hot latch
#

OH

somber coyoteBOT
#

KirbysGames

hot latch
#

and then she divided

tall coral
#

yep!

hot latch
#

okay wow

#

and so i get the x value so how did she get 819

tall coral
#

chuck it back into the original equation

#

$\tan (63) = \frac{y}{417.5949}

hot latch
#

tan63=y/417 ?

tall coral
#

yep

hot latch
#

omg

tall coral
#

then solve y

hot latch
#

wow im slow

#

thank you

tall coral
#

you're good, we all have those moments lol.
and you're welcome

hot latch
#

have a great night

feral oxide
quartz minnow
#

I got a doubt in circles

obsidian harness
quartz minnow
#

Why's there 2/3 ad= 2/3 BC and so on

obsidian harness
#

EM:DC = 1:2
so by similar triangles, EG:GC = 1:2

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similarly for the other sides

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cause it doesn't matter which points you label as A, B, C

fringe perch
obsidian harness
#

you get ignored or someone just gives you the answer

#

without the solution

#

and don't expect people to give you a solution cause you could have pasted this question here in 2 secs and just left

#

without doing anything else

fringe perch
faint pasture
fringe perch
#

anyone

#

i have a doubt

#

can anyone help me out

obsidian harness
fringe perch
#

i think the answer is b

#

@obsidian harness

obsidian harness
#

idk man

fringe perch
#

ok

#

why no one is responding btw?

obsidian harness
#

no one wants to do JEE stuff if it's not their homework

faint hollow
# fringe perch

I actually like doing JEE stuff but I dislike pure geometry and 3d stuff,conics pretty good

faint hollow
#

Yeah if,it's pretty common, whoever I ask has the same opinion except some exceptions here and there

#

Btw which grade you in @fringe perch

fringe perch
#

You?

faint hollow
#

12

fringe perch
fringe perch
faint hollow
#

Yeah ik

fringe perch
#

Hm

oblique widget
#

Somebody please explain to me asap

upper karma
oblique widget
#

SO I SET ALL THE EQUATION TO 20?

upper karma
#

NO

oblique widget
upper karma
#

NOT 20

#

22

#

ONE SEC

oblique widget
#

OH YEA

#

PMG

upper karma
#

ARE YOU TAKING A TEST?

oblique widget
#

NO BRUH

upper karma
#

Oh it's just practice

oblique widget
#

I wouldn’t be able to use my
Phone

upper karma
#

Yeah you're right

#

Sorry I'm kinda dumb

#

I don't actually know but I'll try

oblique widget
#

So can you help me

upper karma
#

Gimme a few mins

oblique widget
#

Ok

#

Did u get it

upper karma
#

Nope šŸ˜‚

#

I'm trying

fringe perch
oblique widget
#

Ok

#

So

upper karma
#

It still gets messy

oblique widget
#

3x-2=x-w+1

#

Then

#

2y+1=3-4w

#

Right

fringe perch
upper karma
#

I got 71/9

oblique widget
#

Photo math said 7

upper karma
#

Man

#

What the flip

fringe perch
#

X is 2 and y is 3 it's seems

#

Ab is 5?

#

@oblique widget

oblique widget
#

IDK

upper karma
#

It's 7

oblique widget
#

HOW

#

HOW

upper karma
#

Trust photomath fr

fringe perch
#

Sry 7

oblique widget
#

HOW DO I FIND IT

upper karma
#

One sec

fringe perch
#

The source is correct

#

Il send u wait

oblique widget
#

OKK

upper karma
#

Wait photmath is wrong

oblique widget
#

Are you guys searching it up

upper karma
#

Possibly (No)

fringe perch
#

@oblique widget here u go

#

Got it?

oblique widget
#

Let me look

upper karma
#

Nope

oblique widget
#

Where did the 2 come
From

fringe perch
fringe perch
oblique widget
#

The first step distributive property

fringe perch
#

You see 2l +2b= perimeter

oblique widget
#

Why is it l and b

fringe perch
#

Take the 2 out as common

oblique widget
#

I have different variables

fringe perch
oblique widget
#

You wrote wrong

upper karma
#

The idea is the same

#

He used different variables

oblique widget
#

I DONT UNDERSTAND

fringe perch
upper karma
#

this problem is dumb

fringe perch
upper karma
#

I didn't solve for each individual variable

fringe perch
#

And i took 3 minutes to solve it

oblique widget
#

My teacher didn’t even teach this

upper karma
#

What i did was make x=(w+3)/2

#

But

#

I give up

#

Everytime I do the problem over, I get different values for x and y

oblique widget
#

AHH

#

ME TOO IM TRYING TO SOLVE FOR W TO PLUG IT

upper karma
#

W might say -11/9 so at this point I'm giving up

#

Best of luck

oblique widget
#

NOOOOOOOOO

#

@fringe perch help

fringe perch
#

What is it?

#

@oblique widget

#

What is it?

oblique widget
#

Sorry

#

Help me with the problem

#

Like explain it verbally

#

@fringe perch

fringe perch
#

Verbally?

oblique widget
#

Like text

fringe perch
#

Ask someone else , I'm not good at English!

fringe perch
oblique widget
#

Don’t write it on paper just like tell me step by step

fringe perch
#

Gimme 5 ninutes il

oblique widget
#

And I write as u say

fringe perch
#

Can I get the digital copy of that question pls!

#

@oblique widget where have you gone?

oblique widget
#

Uh whag do you mean digital

oblique widget
fringe perch
#

I mean send me the question

#

Il explain u

oblique widget
fringe perch
#

First let's take ad as l

#

And ab as b

#

We know that 2(Ab+Ad) =22

#

Ab +ad =11?

#

@oblique widget

oblique widget
#

Ok

fringe perch
#

So you could apply the value of ab and ad in the equation we got

#

You'll get

#

2y+1+3x-2=11

#

Solve this

#

@oblique widget

#

Did you get it?

oblique widget
#

One sec

fringe perch
#

Make it fast

#

I should sleep

oblique widget
#

Oh sorry I can just do it myself then

fringe perch
#

Wait Ill finish it off and go

fringe perch
oblique widget
#

o

#

Ok

fringe perch
#

Just plug some random values and see if it's equal to 12

#

If u plug in x as 2 and y as 3

#

Youll get 12?

#

So we can conclude that y =3

#

Line ab =2y +1

#

=7

#

Any queries?

#

@oblique widget

oblique widget
#

Ok

fringe perch
#

Got it?

#

@oblique widget

#

Or any doubts u have?

oblique widget
#

I’m doing ab = cd

#

Then ad =cb

faint pasture
#

It said sonething like

#

Error 404 brain not found

fringe perch
faint pasture
fringe perch
#

I got no brain too

#

How does it look like?

faint pasture
#

Its looks grey

fringe perch
#

How do u know if you don't have one?

faint pasture
#

You grey me grey everything grey

fringe perch
sour hearth
tiny tartan
#

Hey friends is there any way I can complete straight lines chapter in one day?

#

I have my maths exam in 10 days and I am cooked

#

• Basic concepts of Points and their
coordinates.
• The straight line

  • Slope or gradient of a line.
  • Angle between two lines.
  • Condition of perpendicularity and
    parallelism.
  • Various forms of equation of lines.
  • Slope intercept form.
  • Two-point slope form.
  • Intercept form.
  • Perpendicular /normal form.
  • General equation of a line.
  • Distance of a point from a line.
  • Distance between parallel lines.
  • Equation of lines bisecting the angle
    between two lines.
  • Equation of family of lines
  • Definition of a locus.
  • Equation of a locus.
#

This is the syllabus

graceful talon
raw slate
# tiny tartan • Basic concepts of Points and their coordinates. • The straight line - Slope ...

Morning (3-4 hours):
Basics First
Points and Coordinates: Just do a quick brush-up here, maybe 30 mins tops.
The Straight Line:
Slope/Gradient (30 mins) – get how to calculate and why it matters.
Angle Between Two Lines (30 mins) – learn the formula and maybe run through a few examples.
Perpendicularity and Parallelism (30 mins) – focus on those conditions.
Line Equations (1-1.5 hours):
Cover all the forms: slope-intercept, two-point, intercept, perpendicular/normal, and general form. Make sure you can convert between them smoothly.
Afternoon (3-4 hours): Application TimeDistance Problems (1.5 hours):
Point to Line Distance (45 mins) – know the formula and practice.
Distance Between Parallel Lines (45 mins) – same deal, understand then practice.
Advanced Line Stuff (1.5 hours):
Equation for Lines Bisecting Angles (45 mins) – get the concept and practice.
Family of Lines (45 mins) – focus on deriving and using the equations.
Evening (2-3 hours):
Locus and Review
Locus Problems (1.5 hours):
Definition + Equation (1 hour) – dive into understanding and deriving equations.
Quick Review + Practice (30 mins) – hit the key points again and do a few problems.
Final Hour: Recap & Test urself:
Go over formulas and concepts quickly. Do some mixed problems to see where you're at.

raw slate
raw slate
thorn aspen
#

I am NOT spending an hour and a half on line equations

dense smelt
#

How are lines m and l parallel

obsidian harness
#

hence AC is the diameter of the circle

#

the diameter makes an angle of 90 degrees to both of the tangents

#

hence proven

#

by angles in the same segment, it doesn't matter where point D is

mellow quest
dense smelt
obsidian harness
dense smelt
#

How does the diameter making 90 w the lines tell us there parallel

#

And wasn’t that the diameter making 90,s alr given

obsidian harness
dense smelt
#

Or can we not assume that

obsidian harness
#

I mean if the angles were different, you could have something like

dense smelt
obsidian harness
#

actually there's an even simpler way that I overlooked cause I thought it was assuming the q

dense smelt
#

Dang I gotta stop assuming stuff

obsidian harness
#

draw a parallel line to line l through point B

#

oh wait I think that's assuming what we want to prove

dense smelt
#

I was trying to make a line through b and show that l and m are parallel to that so then l and m are parallel but it didn’t work

obsidian harness
obsidian harness
#

the problem is that you can't show that the two perpendiculars coincide

#

so you haven't shown you have a straight line through B

dense smelt
#

Wow

#

It’s so easy to assume in geometry

#

Thanks for explaining this tho

obsidian harness
#

btw I found AOPS's solution

obsidian harness
dense smelt
empty yew
#

How to prove $\sin^{2}A + \sin^{2}B - \sin^{2}C = 2 \sin{A}\sin{B}\cos{C}$

somber coyoteBOT
#

KingDanger

empty yew
#

Hi @obsidian harness After long time

#

My work

obsidian harness
#

approach0 is goated

#

hah I was thinking of the circumscribed radius approach

#

and someone answered, slick proof

faint hollow
#

Why the hell did you not write the given condition

#

it felt like something was missing

obsidian harness
#

it's kind of obvious if you've seen enough of these

#

that ABC is a triangel

faint hollow
#

I know, I have proved it in the past

#

But you never assume

empty yew
#

What is circumscribed radius approach?

somber coyoteBOT
obsidian harness
#

oh circumradius I can't English

empty yew
#

I have the topic law of sines and cosines in my later topics but now I want to solve this with sum or product and conditions

steady vault
#

ez

odd horizon
#

how do you get the first step

faint hollow
faint pasture
#

Cuz its pretty doable use sin4x = 2 sin2x cos2x

#

Now try to express this in terms of only tan

#

Similarly you can do cos

odd horizon
odd horizon
faint pasture
odd horizon
#

hmm

#

OH

#

i see

#

i forgot

#

oops

#

thanks

quartz minnow
#

I need help with the one marked with H

hoary prism
hoary prism
#

Nice

hallow ridge
#

does anyone know what the Sc on question e represent?

grave mulch
#

I need help with this question, your supposed to use this format to find the answer: y=ax+b

verbal tapir
#

so, first we know one point is on (-1,2) and the other on (3,5)

#

the slope of a line that connects these two points are (5-2)/(3-(-1))

#

=3/4

#

thus, a, which represents the slope, is 3/4

#

to find the b, we can replace y with (y-y_1) and x with (x-x_1)
(y_1 and x_1 are the coordinates of one of the two given points, although any point on the line works)

#

for this solution, i'll use (3,5)

#

so, y-5=(3/4)(x-3)

#

expand this to get
y-5=(3/4)x-9/4
add 5 on both sides to get the final equation
y=(3/4)x+11/4

#

i should learn how to use the latex bot

grave mulch
#

i understand now thanks

#

but i use this method which is very similar to yours

verbal tapir
#

yeah that also works

#

as far as i know, there are a lot of methods but all of them involve using the two points to find the slope and then one to find the y intercept

#

(at least all the methods i know)

prime stratus
#

the number 5

verbal tapir
#

i don't believe this goes here

#

but sure

#

in an arithmetic sequence, given a term aā‚™ (where n is not 1), aₙ₋₁=aā‚™-d and aā‚™ā‚Šā‚=aā‚™+d

#

aₙ₋₁+aā‚™ā‚Šā‚ = 2aā‚™-d+d = 2aā‚™

#

Thus, 7x-1+6x-9 = 2*8 = 16
13x-10=16
13x=26, x=2

#

Therefore,
8x+2=18
7x-1=13
8
6x-9=3

verbal tapir
obsidian harness
#

<@&268886789983436800> spam link

surreal void
#

Hello

full nymph
#

hi

kind quail
#

Hello

tribal rose
#

How do you reflect shapes over a diagonal line?

gusty spruce
tribal rose
gusty spruce
#

I was confused on where the origin was

tribal rose
#

I'm confused as to how to do diagonal reflections.

gusty spruce
tribal rose
gusty spruce
#

I’m honestly a little confused so I just went to the points

#

Then the rest is self explanatory

tribal rose
#

It looks kind of like a 90-degree rotation.

gusty spruce
#

I saw it like that yeah

verbal tapir
#

just gonna say this

#

the reflection does seem similar to a rotation, but without some sort of symmetry, it is impossible to have two congruent shapes be able to overlap perfectly using only rotation if one is a reflection of the other

#

just to clarify

unique nacelle
tribal rose
#

So it's not really a rotation.

#

I'm confused as to how this works, then.

unique nacelle
#

NOO

#

LOOK!

#

ITS REFLECTION

#

MAKE THE LINE PERPENDICUILAr

#

THEN SAME DISTENCE ON THE OTEHR SIDE

verbal tapir
#

first, we find the foot of perpendicular from P to l
the distance is d

#

extend the line segment by d

#

the end point is P' (the reflection of P)

#

now, other shapes are just a set of points

#

shapes can be reflected like this

#

for polygons, or angled straight lines, reflect each vertex and then connect the corresponding points

#

for other shapes like circles which only require a little information, reflect specific necessary points (like the center of a circle) and use the information from earlier to draw the shape

verbal tapir
#

(assuming the side length of a grid square is 1)

tribal rose
#

Thank you so much! This was really clear.

#

So it's just two points that are equidistant from each other.

oblique widget
#

Somebody like explain this to me

verbal tapir
#

each color represents the different possible parallelograms

twin spindle
#

Im not tripping right? This is correct?

verbal tapir
#

yeah that seems correct

#

(n is an integer)

twin spindle
#

Brooo, why'd my teacher doc me 😭😭

oblique widget
#

what the fart why did nobody help me

verbal tapir
#

the graph shows the three possible pointsfor the triangle to be half of a parallelogram

twin spindle
#

How abt problems like these? Cause doesn't the sin and sin-1 cancel?

#

Which jus leaves the degree

verbal tapir
#

no

#

keep in mind the range of sin^-1

twin spindle
#

Yeah -pi/2<Ćø<pi/2

verbal tapir
#

because sin is a periodic function, different angles can have the same sine value

twin spindle
#

So it would jus be sqrt(2)/2

verbal tapir
#

which means the value of a sin^-1 function can never be -225 degrees

#

(or its equivalent in radians)

twin spindle
#

Right?

verbal tapir
#

yes exactly

twin spindle
#

Which would be -60⁰

verbal tapir
#

its

#

-45 actually

#

but yeah that is the idea

twin spindle
#

Wait your right mb mb 😭😭

verbal tapir
#

dw that happens

twin spindle
#

But that would be undefined, right?

verbal tapir
#

5?

twin spindle
#

Cause a value has to be less then 1 if you were to take the cos-1 right?

#

Yeah

verbal tapir
#

yeah i think that's undefined

twin spindle
#

Yeah I got it wrong cause at the time I thought the cos would cancel

#

But I woulda had to say "undefined"

verbal tapir
#

ohh ok

#

yeah be mindful of these 'traps'

twin spindle
#

Yeah I fell for hella on this section

#

Like on this one, tbh I had no clue what to do, but I saw cos/sin and immediately thought of Cot(10) 😭

verbal tapir
#

oh

twin spindle
#

But I think you were supposed to apply the complementary angle formula

verbal tapir
#

yeah

#

that gives 1

twin spindle
#

Idk when to apply those tbh

verbal tapir
#

when you are given two values to operate with

#

if the two values add up to 90+360n degrees (or 270+360n) you can assume you might need to use it later on

#

(i believe you do have to take the signs in account for 270)

twin spindle
#

I see I see

verbal tapir
#

sin(Īø)=cos(90-Īø)
sin(Īø)=-cos(270-Īø)

twin spindle
#

I thought this problem you'd have to apply the complementary formula 😭

verbal tapir
#

oh

twin spindle
#

Or I think you do, but I somehow forgot abt the sin

verbal tapir
#

the last question?(question g)

twin spindle
#

The one is cos(90-22.5)

verbal tapir
#

oh

twin spindle
#

Yeah

verbal tapir
#

that one doesn't 'work' because neither 22.5 nor 67.5 are the special angles

twin spindle
#

Oh wrrd they have to be a special angle 😭

verbal tapir
#

you have to use the half-angle formula of cosine from cos(45)

#

either that or

#

draw a triangle

twin spindle
#

How do yk when to apply thaf šŸ’€šŸ’€

verbal tapir
#

when you get angles that aren't 0, 30, 45, 60, 90

#

(or +90n variants of them)

#

you have a few options

#

if the target angle can be split into 2 of the special angles
such as 75 degrees (30+45), you use the addition formula

#

if the target angle is half of a special angle such as 15 degrees or 22.5 degrees (half of 30 and 45, respectively), you use the half angle formula

#

of course, this only applies to numerical values of the angle, if it's given as a variable like Īø, you have to use a different approach for each scenario

#

when learning about formulas and such, it's a good idea to learn or think about what scenario you want to use them in

twin spindle
#

Shi I see I see

#

I didn't think this test would have us apply any sort of formulas on this section

#

Thought it would jus be common angles and finding the values šŸ’€šŸ’€

#

So is this how you would show the work for this problem?

verbal tapir
#

tbh i don't know your curriculum

#

but id say yes

twin spindle
#

This means that we would have had to apply the sum or difference formula

verbal tapir
#

yes

#

exactly

twin spindle
#

On this question

#

Omg

#

I'm pissed 😭😭

#

I sold this test

#

Their were other problems that I screwed up on aswell, but that's because I wrote the wrong values from the unit circle 😭

verbal tapir
#

oh that's rough

#

fortunately, you won't be messing these up in the future now

twin spindle
#

Oh yeah fs

#

I knew I shoulda wrote the values on the unit circle that my teacher gave us 😭

#

Should i ask if I could retake šŸ’€šŸ’€

#

Couldn't hurt to ask, right?

verbal tapir
#

don't know about that myself tbh

#

i only know geometry and a bunch of other miscellaneous stuff

twin spindle
#

Fair

verbal tapir
#

but if you think you should, go for it

twin spindle
#

Alr I might. I got a couple more, How abt these couple of questions?

verbal tapir
#

i don't get how you did the first question

#

considering the value of β isn't shown

#

now, i don't know exactly what the paper means by 'direction'
but the magnitude is just pythagoras applied to 7 and 3

for question 5a, that's just arithmetic

#

if the direction means the direction relative to the positive x axis, the direction of the Q4 would just be tan^-1(3/7)

the angle between the Q5 vectors u and v is given by the formula
cosĪø=(uā‹…v)/(|u||v|)

#

where uā‹…v is the inner product of u and v

twin spindle
#

Their was multiple parts in this section, with using the same cos and sin

twin spindle
verbal tapir
#

yeah

twin spindle
#

I thought all you had to apply was tan

verbal tapir
#

hmm

#

yeah

#

you can make it work with tan too

twin spindle
#

But you would have to add 180 right?

#

Since its in the 2nd quadrant

obsidian harness
#

the intended method is to find cos theta using the dot product then use the Pythagorean identity / draw a right triangle to find tan theta

verbal tapir
#

seeing that the angles are approximate (at least from what i can see)
i think just getting two tan^-1 values and subtracting them should work

obsidian harness
#

there are definitely other methods too

twin spindle
obsidian harness
obsidian harness
verbal tapir
pearl bolt
#

root3 COT^2 - 4COTA + root 3

Guys please help me in solving theis

#

this

obsidian harness
#

oh wait it's 3/4

somber coyoteBOT
pearl bolt
#

root3 COT^2 - 4COTA + root 3

Guys please help me in solving theis
this

obsidian harness
#

also you want this equal to 0 right?

pearl bolt
#

No, COT^2 + TAN^2 = ?

obsidian harness
obsidian harness
pearl bolt
#

root3 COT^2 - 4COTA + root 3

then COT^2 + TAN^2 = ?

Guys please help me in solving theis
this