#geometry-and-trigonometry

1 messages · Page 379 of 1

outer lagoon
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Can someone explain double and half angle formulas and any good way to memorize them

near timber
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why cant i just use the negative angle?

dark sparrow
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you can

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it'll be offset by 2pi from their solution

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but if you're solving an equation of the form cos(x)=c that doesn't matter

near timber
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ohh ive been so confused because when i graphed it one of the awnsers was correct but the (negative) angle one was off by alot

terse breach
#

I'll translate this

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In an ABCD romb, the diagonal AC = 12, the AB side is equals to 3 square roots out of 5. Find the tangent of the angle BAC

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Is this the correct solution?

dark sparrow
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@terse breach is it ok if i respond in russian?

dark sparrow
#

что это у тебя вообще за расчеты?

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откуда взялись числа 45 и 36?

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и откуда взялось, что 9 = 3?

terse breach
dark sparrow
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??

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не поняла

terse breach
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вот пример

dark sparrow
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то есть ты вычисляешь BO по теореме Пифагора

terse breach
#

да

dark sparrow
#

почему бы об этом сразу не написать?

terse breach
#

было бы и лучше так

dark sparrow
#

короче, значения BO и tan(BAC) у тебя правильные. проблема - с оформлением

terse breach
#

Да, у меня получается большой кошмар на доске в школе, хотя решаю правильно

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Спасибо за обзор зато

dark sparrow
#

в работе было указано нецелые ответы писать десятичными дробями? если нет, то я бы записала ответ как 1/2

terse breach
dark sparrow
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лучше так не делать

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простые дроби предпочтительнее

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особенно если что-нибудь типа 1/3...

terse breach
#

понятно

terse breach
dark sparrow
#

в четвертой строчке в пункте 1 вместо плюса должен стоять минус

terse breach
#

исправлено

dark sparrow
#

вот так нормально

terse breach
#

понял

near timber
#

to determine the highest value of 2sin(3x)+cos(3x), do i have to take the derivative and then look for max min values or is there a more efficient way?

dark sparrow
#

sure is

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$a \sin(x) + b \cos(x) = \sqrt{a^2+b^2} \cos(x - \varphi)$

somber coyoteBOT
near timber
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thanks!

upper karma
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why was angle 60 chosen here?

magic lichen
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cuz theta' ig

terse bane
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Line h goes through point (0, -k) and has a gradient of 1. If that line is tangent to the circle which equation I already sent above, then the value of eight times all possible values of k is?

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the radius is an imaginary number which means the circle doesn't even exist, but can you get the answer anyway?

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here's the slope intercept form of the line

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then just substitute it to the equation

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and since the line is tangent to the circle, that means the discriminant is equal to 0

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and the value of all possible ks multiplied is

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since they ask for the value of 8 times all possible values of k

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is this a valid answer?

vestal siren
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#3-12

vestal siren
whole granite
# vestal siren #3-12

try to show some effort, or at least split the questions, it'll help you to get help

vestal siren
#

okay

vestal siren
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like put it in sections

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?

whole granite
long parcel
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Could somebody pls explain this to me ?

vestal siren
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okay

soft marten
vestal siren
desert shore
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this is kind of silly but does anyone understand what this question is asking me

formal hatch
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Hello, I am just a bit confused, in the textbook (french) it says that the value of the angle between vector u and vector v is 7pi/12; But I don't see how

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It says that the angle between two vectors is the smalles angle theta when they have the same origin

honest thistle
desert shore
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No i meant c in specific

honest thistle
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just do t=0 lol

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should be just before the time of launch

desert shore
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thats what i assumed but needed to make sure im understanding this correctly

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ty

honest thistle
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do you have the answers?

desert shore
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no

honest thistle
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well i would do t=0 idk about what else we could do

onyx wasp
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Anyone who knows the name of this figure? It’s supposed to be a topped off cone with a curved side

signal swallow
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frustum

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oh wait curved side

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:(

onyx wasp
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The side is a x^2 curve

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And I can’t find it omg

honest thistle
# long parcel

lets say sinx = a so the question becomes a quadratic formula:
6a^2 - 5a + 1 = 0
if we solve for a we get 3a = 1 and 2a = 1 so a= 1/3 or 1/2

signal swallow
#

don't do people's work for them

honest thistle
# vestal siren

for 12
from the B point draw a line to |AC| so that it makes a 90° angle lets call the point that it contacts as D.
DBC angle is 45° and you can try to find |DA| from 30 60 90 triangle and get |DC| along with |DB| and find tan45

honest thistle
signal swallow
vestal siren
#

dang 💀

north heart
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lmfao

crisp turret
#

How would one solve a problem like this

tall coral
#

It's between pi16 and 324 if that helps at all
Idk how to solve it though

tall coral
#

shouldn't be that bad from there

tall coral
#

wait nvm

low jungle
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hey why cant arcsin have its range restricted to [π/2,3π/2] instead of [−π/2,π/2] it would still be injective right?

dark sparrow
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do you mean [+pi/2, 3pi/2]?

low jungle
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yeah my bad

dark sparrow
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well you could take the inverse of the restriction of sin to [pi/2, 3pi/2] sure

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that exists

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it's just different from the canonical restriction

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and is somewhat less elegant

low jungle
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i see.. so its just a convenient convention of sorts right?

dark sparrow
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essentially yes

low jungle
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alright thanks!

compact jasper
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that is identity rule ? sin(a+b)=sinacosb+cosasinb
but why ? why just not sin (a+b) = sin(a) + sin(b) 🙂

nocturne remnant
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Why not?

dark sparrow
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sin(a+b) = sin(a) + sin(b) is simply not true lol

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sin(90°+90°) ≠ sin(90°) + sin(90°)

nocturne remnant
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“Hey god why didn’t you make sin(a+b)=sin(a)+sin(b) that would make things so much easier bruh”

mild briar
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Just like (a+b)² = a²+b²

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It would be pretty, but it's not reality

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Not to mention, that would imply sin(x) = λx for some constant λ

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Which would bode ill for the shape of circles as we know them

simple rain
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are supplementary congruent angles right

slate phoenix
#

In geometry, the Pitot theorem, named after the French engineer Henri Pitot, states that in a tangential quadrilateral (i.e. one in which a circle can be inscribed) the two sums of lengths of opposite sides are the same. Both sums of lengths equal the semiperimeter of the quadrilateral.The theorem is a logical consequence of the fact that two ta...

lethal robin
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does anyone know how to approach geometrical questions that want you to proove something

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i look at the question, i think about how i can solve it

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no methods help

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then i look at the solution and it seems so obvious

simple rain
lethal robin
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Aight

lethal robin
lethal robin
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The question doesn't have a diagram.

fleet idol
#

Can anyone explain me how to calculate side BA please?

trim breach
vagrant ore
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Is the answer 1 line?

trim breach
pastel pewter
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can some one help me to find the measure of the angle between the diagonal of trapezoid inscribed in circle?

light fable
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what did you try?

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you were on the right track using cos

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what's the equation with cos from soh-cah-toa?

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right, and what is it in your case, with those labels

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I mean write the equation about cosine

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with your given diagram

wheat walrus
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similar concept

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write out the cos equation you would use to solve for x

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are you still on this question?

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you’re just solving for x right?

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you’re not going to use inverse cosine (cos -1) when trying to figure out a side length

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should look something like this

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you only need to do inverse sin, cosine, or tangent when figuring out angle measures

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side lengths are simpler

light fable
#

^ that's the way

wheat walrus
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that’s good, the more practice, the better

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yea what you have in looks right

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the horrors of deltamath

outer bison
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i gotchu

north heart
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the angles of a triangle add up to 180

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that's all ya need

outer bison
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im in algebra 2 so im not 100% sure but add all those degrees up and is all equal to 180

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and solve for x

wheat walrus
#

YOOOOOOO

north heart
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motherfucker this a test?

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<@&268886789983436800> not sure if it's a practice exam or smthn?

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but ig i should ping

silk charm
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banned

ember stratus
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To locate a whale, two microphones are placed 6000 feet apart in the ocean. One microphone picks up a whale's sound 0.5 second after the other microphone picks up the same sound. The speed of sound in water is about 5000 feet per second.

a. Find the equation of the hyperbola that describes the possible locations of the whale
b. What is the shortest distance that the whale could be to either microphone?

wheat walrus
daring wind
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can there be an algebraic expression for

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cos(20°)

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i don’t care how complicated it is, as long as it uses all real numbers and functions

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like how cos(45°) is sqrt(2)/2

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something like that, but for cos(20°)

wise pawn
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I'd probably look at trying to work something out of the real part of the corresponding cyclotomic polynomial

grave pond
#

cos(20°) is the real part of an 18th root of unity, so it is certainly algebraic.

grave pond
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However, the minimal polynomial for cos(20°) is 8x³-6x-1. It has 3 real roots (namely the real parts of the other primitive 18th roots of unity), so it is a casus irreducibilis where the roots of the polynomial cannot be expressed using real radicals only.

stiff tulip
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I’m quite unsure tackling how to solve for X when it’s in the exponent

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In example, “Solve for X” 10^3x=25

grave pond
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That's not even an equation.

stiff tulip
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Oop

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Brb

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It says round nearest hundredth

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Do I begin by cube rooting ?

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I got log(2.92)=X

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X=0.47

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I’m not sure if it’s correct or not

grave pond
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Punch it into a calculator and see if you get 25 as you should.

stiff tulip
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Yeah sort of

grave pond
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But closer than either 0.46 or 0.48 gets you.

silent plank
#

ideally you'd avoid rounding in the intermediate steps

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and use
x = log(cbrt(25))

grave pond
#

You get a slightly nicer expression if you start by taking the logarithm: log(25)/3.

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(Which of course has the same value).

stiff tulip
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Oh ok

pallid pilot
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chat any idea how i can get AE if i have AC equals 25? (ignore the writing down there)

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chats dead

wheat walrus
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oh what’s up

simple holly
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i fucking hate geometry dash

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awful game

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ruined my life

wheat walrus
#

that’s about the only way i see it

timid escarp
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Yo I’m in accelerated algebra 1 and I might take geometry next year is there any thing I should know before hand like things that are gonna be annoying

unborn heath
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depending on the teacher u might have alot of memorization as theres a decent amount of theorems and angle relationships

lean quarry
#

Guys do any one of you have, the formulas of triangle
Like

Areas

Similarities

Medians
Bisectors

And plenty more, all in one file ?

glacial otter
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<@&268886789983436800>

slender wasp
#

tagging 8 times

silk charm
#

why are you pinging random people?

weary drift
#

man

gaunt lion
#

that was quick

daring wind
#

is it possible to solve binets formula for x

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it’s like

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coukd you solve this for n

daring wind
grave pond
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What do you mean by solve here? If you have a large Fibonacci number and want to know which it is, in practice you can just ignore the ((1-sqrt(5))/2)^n term -- it goes to zero for large n anyway.

grave pond
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Hint: It's a red herring that one of the lines goes through the center of the circle.

rocky tide
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I can't understand those two different question can someone help me plz?

odd dust
#

What it supposed to be 148 degrees?

heady forge
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What don't you understand ?

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Let's start with the first one @rocky tide

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Ask anything.

vagrant ore
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I need help with this

heady forge
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Try to form two triangles

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That could help

vagrant ore
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How would that help? I tried it

heady forge
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X= 60°

vagrant ore
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Oh I was just going to say that lol

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I noticed that it did make two 30 60 90 triangles

heady forge
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Tangents that extend from the same point are identical

vagrant ore
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I didn't see that at first

heady forge
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They form identical triangles

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And from this we extract the following

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x+β=180°

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β is 120° in our case

rocky tide
#

Is the first one good
cos(30°) = MN / 10
10 cos(30°) = MN
10 (0.866) = MN
8.66 = MN

heady forge
#

Yes

rocky tide
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@heady forge can u explain me this one pls if I am not borthing you .

heady forge
#

What do you want me to explain?

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You are welconed

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Welcomed

rocky tide
heady forge
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You try to find X?

rocky tide
#

I think so

heady forge
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Because there is no question. I'm assuming you need to find value of x

rocky tide
#

Yeah it should be it

heady forge
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Ok

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Cos40°=X/10

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0,766=X/10

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X=7,66

rocky tide
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Thx man but if I get the question in sin=but in fraction will it work with the formula u make.

heady forge
#

Since we know Hyp and an angle and we need to find adj,we take cos40°

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What do you mean?

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If you get sin then you have
Sin40°=BA/10

rocky tide
#

Like the question is similar but just numbers are in fraction

heady forge
#

Oh

rocky tide
#

Wait

heady forge
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You will multiply fraction with 180°

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And then replace the answer

rocky tide
#

Like this

heady forge
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So

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(15/17) multiply by 180°

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And then same process

rocky tide
#

Ohhhh thx man

heady forge
#

Np

rocky tide
#

I got 15/17 X180
=2700/17x1
=158(14/17)

heady forge
#

Then we take the formula

grave pond
#

What? 15/17 is the cosine, not a fraction of a circle (or of a straight angle).

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You don't even need to know the angle in degrees because the problem is telling you the values of all the trig functions.

heady forge
#

Oh yes

grave pond
#

The only thing you need to do is know which of them to use.

heady forge
#

Oythogoren theorem

grave pond
#

Pythagorean? Not even that.

heady forge
#

Cos =adj/Hyp=15/17

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And then replace Hyp with 34 and adj with y

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If I remeber correctly

grave pond
#

y is the side opposite to angle A, not the adjacent one.

heady forge
#

Then take sin

grave pond
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@rocky tide, are you still here?

rocky tide
#

Yeah

heady forge
#

Sin=opp/Hyp=y / 34=8/17

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Solve for y

rocky tide
#

My level is grade 9 so by far in trigonometry I had learn Pythagoras theorem

heady forge
#

Sorry,I thought that the angle was 15/17 rad. My apologies

grave pond
#

You don't need Pythagoras for this, but you do need to know what sine and cosine are.

rocky tide
#

How to solve then

heady forge
#

SinA=opp/hyp

vagrant ore
#

Is the answer circle?

grave pond
#

Yes.

vagrant ore
#

Thanks

rocky tide
heady forge
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SinA=y/34

grave pond
#

No, there's no 180.

heady forge
#

No forget that

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8/17=y/34

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solve for y.

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@grave pond my bad!

north heart
heady forge
#

So y=16cm

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That's your answer.

rocky tide
#

The 34 need to be divide by a number right

heady forge
#

Just gave you the solution.

grave pond
#

It's not good to go all the way to a complete answer just because the asker isn't getting it.

north heart
#

^

heady forge
#

@rocky tide I'll write it down again :

sinA=opp/Hyp(1)

sinA=8/17
opp=y
hyp=34

So we put all of these at (1) and solve for y
So y=16

rocky tide
#

Yes 8x2

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Is 16

heady forge
#

No it's 8/17=y/34

rocky tide
#

34 dividend by 17

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2x8

grave pond
#

Yes.

heady forge
#

Yes,you got it

rocky tide
vagrant ore
#

I need help

north heart
#

look up the inscribed angle theorem and use properties of triangles for the rest

vagrant ore
#

Wait I mean 20

north heart
#

idk im not gonna do it lmao

#

if it checks out then probably

vagrant ore
#

Wdym checks out?

north heart
#

oh

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yeah

#

it's 20

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lmao

#

i think you're supposed to use something much simpler than inscribed angle lmao

vagrant ore
#

Lol

silent plank
#

inscribed angle is one of the simplest things to apply

north heart
#

im 99% sure they're meant to use basic trig lmao

grave pond
#

Could you show the solution you think is simpler than the inscribed angle theorem?

north heart
#

by simpler i mean uses just trig and properties of triangles

grave pond
#

I don't understand what it is you're proposing.

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What could possibly be simpler than "divide this number from the figure by two and you're done"?

north heart
#

im not proposing anything, i'm just saying that i think they were expected to use just trig and triangle properties to solve

north heart
grave pond
#

You're saying that you think they are supposed to use a method that you refuse to reveal what is?

north heart
#

?

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fine i'll try and find it lmao

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gimme a bit

gritty plinth
#

Can someone please check a problem for me quickly?

north heart
#

i probably should've known better than to go about disagreeing with tropo

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i genuinely thought there had to be a simpler way >.>

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but i dont think it's possible to do w/out inscribed angle

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my b

vagrant ore
#

I need some help

grave pond
#

draw another secant line (connecting two of the points on the circle that don't have a line between them yet), derive more angles using the incribed angle theorem (I think a pattern is showing by now), and you will be able to find x using the angle sum of a triangle.

vagrant ore
#

Is it 15?

grave pond
#

Hmm, that's not what I get, but I might be missing something. What's your reasoning?

vagrant ore
dark sparrow
#

looks can deceive

#

also there are no triangles here

vagrant ore
#

I remembered what to do and got 26. Is that right?

dark sparrow
#

seems ok now

vagrant ore
#

Ok thanks

celest radish
#

Help

hidden crypt
celest radish
#

Did help somewhat but still couldn't solve it

hidden crypt
#

What did you get?

silent token
#

help mee pandaOhNo

#

if O= 26,656° find (x+y)/z approximately

celest radish
acoustic jungle
#

not sure why they chose the value 26.656, seems kinda stupid.

hidden crypt
celest radish
hidden crypt
#

you can get something better

#

sin2x+2sin2x*cosx=sin2x(1+2cosx)

azure crown
celest radish
hidden crypt
celest radish
#

Oh damm

silent token
acoustic jungle
hidden crypt
silent token
#

I did it again, okay? @acoustic jungle @hidden crypt

#

So it's option C? 1,9?

vagrant ore
#

I need help solving this

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Not really

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I know you're supposed to take half of 6y

vagrant ore
#

I solved it

mystic shadow
#

$$\cos(x)-\cos(y)=\frac{5-\pi}{10}$$

somber coyoteBOT
#

MiracleMan

mystic shadow
#

$$\cos(5x)-\cos(5y)=\frac{1}{2}$$

somber coyoteBOT
#

MiracleMan

mystic shadow
#

This is easily solvable by plotting

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I was wondering if this was analytically solvable

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I know 0 < x,y < pi/2, and y>x

dire hull
#

Is it okay if I ask for help here and trig 😅

upper karma
somber coyoteBOT
rare sierra
#

can someone give me the equation I can use to solve this because their explanation is bogus?

#

I know in this scenario
A= 18/30
B=15/30

tulip vector
#

hello, I'm having a bit of a problem on this one. If there are two equal sides/angles the "N", what should I do? My answer is supposed to be largest to smallest order

valid harbor
#

what

#

can you clearly state your problem

polar jewel
#

Please help! I dont know this topic. Need this asap!!

#

Also the part of what i sent

trim breach
spare moss
#

I want to calculate this integral, but could you help me with the visualization?

#

How could it be drawn?

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it is the shape which is restricted by axis

merry dew
silent token
#

LO= 9 (1)-3 = 6

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64=8+7x
56=7x
x= 8

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m <NPI = 8+7x = 8+7 (8)= 64

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I think

molten marsh
#

can anyone help

#

nvm i got it

terse breach
worthy siren
#

hey, I need help on some math homework thats due in an hour. Im currently in the unit of adding vectors, and we recently learned sine cosine and tangent, which we're supposed to use for this example. How can I do it?

hollow vortex
#

you can use pythagoream theorem to find the magnitude of the movment

orchid gate
#

in geometry of triangle what this value mean?

somber coyoteBOT
#

Ausländer

proud plover
#

Guys is my solutions correct?

#

Can anyone help me?

upbeat helm
nova aurora
#

can someone help

sterile orchid
#

can someone pls help me with this question, i've drawn a diagram but i do not think i have the right equations:

dark sparrow
#

so far so good

#

what equations did you get for AB and AC

upper karma
#

can someone help me pls ?

clear lark
#

Hi, I agree with your answer. I wonder if there is a typo and the coordinates of D are meant to be (-2,-2)

upper karma
#

they are all incorrect

errant flare
#

How?

past charm
#

im pretty sure i've seen something similar on youtube

#

like mind your decisions probably

errant flare
past charm
wanton jetty
#

Can someone please help me with these 2 questions

vestal siren
#

can someone check my work

trim breach
#

Actually, looking at it, all of them are.

#

The opposite side is one the angle does not touch.

#

Though the second triangle seems right, but you still labeled the sides incorrectly. And I think your final answer is incorrect as well.

vestal siren
#

i'm still confused

trim breach
vestal siren
#

oh alright thank you

trim breach
#

“Adjacent” means “next to”.

#

Many of the steps you did were right, but you just flipped opposite and adjacent when you labeled them, so you ended up using the wrong ratio.

vestal siren
#

oh alright bc

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wait can you show me an example how to do one

trim breach
#

@vestal siren

vestal siren
#

okay thank you

sterile orchid
dark sparrow
#

........

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okay so that took me some time to decipher.

#

seeing as that's nearly a full day later you're saying this

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but whatever

#

do i understand correctly that you have actually written down The equation of line AB is y = am + c as part of your work, or did you just blurt that out

sterile orchid
#

yeah i wrote it like that

#

sorry it's y=-am+c because the x value is -a

#

also line AC would have the same equation

dark sparrow
#

what is m?

sterile orchid
#

i don't know i don't have any definite coordinate just variables

dark sparrow
#

.....

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so you're writing things whose purpose you're not even aware of.

#

strange!

sterile orchid
#

no like that is the equation of the lines with the information that is currently known to me

dark sparrow
#

anyway, i think you're confusing the equation of the line itself with what happens when you plug one of your points into it.

sterile orchid
#

hmmmm, what do you recommend that i do then?

dark sparrow
#

consider point A and its coordinates first and foremost

#

and then the angles made by AB and AC with the x axis

sterile orchid
#

right right, i am sure that i have no idea what the coordinates of point A are apart from the fact that the x value is greater than a

dark sparrow
#

the medians of your triangle intersect at the origin

#

and the intersection point of the three medians of a triangle divides each of them in a 2:1 ratio

sterile orchid
#

sorry i dont think i understand lmao my b

#

medians?

dark sparrow
#

the lines in a triangle that connect each vertex to the opposite side's midpoint...

nocturne remnant
#

What “further depth” do you mean exactly

#

Are you struggling with something in particular?

#

What equations?

#

The unit circle definition of sine and cosine is much more general and powerful than the “ratio of sides in right triangle” definition that students are usually introduced to

#

So just think of using sine and cosine to solve for triangle sides/angles as an application of trig functions, not the definition of trig functions itself

nocturne remnant
#

true

#

Whereas if you look at something like uniform circular motion it’s much more sensible that the derivative of sin would be cos

muted sail
#

Still confused by this.

#

I dont remember the formula on how to find surface area of cone. ;-;

upper karma
#

Where l is the side of it (e.g the 11cm on the 1st one)

#

The 𝝅r² is the surface area of the circle face so if you cone is open at the end you don't need to use it

#

Hope it helped a little :)

muted sail
#

thanks :D

upper karma
#

By any chance they don't give you the 'l' side just use Pythagoras assuming they would atleast give you the height for it

muted sail
#

I dont really get what it means by show your awnser in terms of pi

upper karma
#

Oh usually your answers on your calculator will have 𝝅 with it since it was multiplied in

#

Just don't hit the S->D button (the button that converts fractions to decimals, still don't know the name of it lol)

#

Basically they dont want decimal answers

muted sail
#

oh, okay.

upper karma
upper karma
#

Can someone help me out with this?

#

I just don't know how to set up the equation

trim breach
#

So BD = 2BE

upper karma
#

So I just double the equation of BE?

#

Okay

#

Got it

upper karma
#

hello

#

does anyone know about circles

fallen sleet
#

given an arc, is it possible to construct with compass and unmarked straightedge the circle upon which it lies?

#

this works

fallen sleet
#

i understand now

wicked fossil
near sand
#

Hi, so I'm working on the first one (finished the other two) and I'm a bit confused as to what to do, even with the hints. If someone could help, that would be much appreciated

#

,rotate

somber coyoteBOT
warm plinth
#

I've been trying to solve this and i found a contradiction when i tried 2 different approaches, i cant manage to find the mistake thinkspin

#

This is all the information i got, heres the original exercise, (its in italian)

#

,rotate

somber coyoteBOT
warm plinth
#

"A right pyramid has as its base a square with a diagonal of 18(sqrt2)cm. The hight of the pyramid is 1/2 of the hight of its triangles, find the volume of the pyramid in exact values."

#

I found only 2 approaches and one of them involves trigonometry, which we havnt learnt yet.

#

Exact values is like 10(sqrt2) not ≈14.14

warm plinth
#

I just realised that i might be in the wrong channel

dark sparrow
#

no, this is ok

#

your question is very clearly geometric

runic beacon
#

ok, so i am not sure if my approach is correct, but, the diagonal of the square should give you the side (by the pythagorean theorem) So, now let the height of triangle be y and then height of the pyramid will be 1/2 * y.
Now the centre of the square, the height of the triangle and the height of the pyramid also form a right angled triangle in a different plane.
So, height of pyramid by the pythagorean theorem, as in (1/2 * y)^2 + (1/2 * 18 )^2=y^2
solve for 1/2 y , you will get, height of pyramid
Then you can apply the formula for volume

warm plinth
#

Oh i tought i had to ask in #help

dark sparrow
#

no

warm plinth
#

Oh ok 👍

warm plinth
runic beacon
#

it is half of the base

warm plinth
#

oh and by hight of the triangle i mean the "apotheosis" i didnt know the word for it

runic beacon
#

what is the apotheosis?

warm plinth
#

wait google translated f-ed up lmao

#

i meant the apothem

runic beacon
#

then i think i need to think what i have done

warm plinth
#

Heres everything i tried so far (all giving me contradicting results) i have in 'a' the apothem

#

(Btw the dot (•) is multiplication)

#

The hight of the triangle is the apothem

#

Thats what i meant by hight

runic beacon
#

i was talking about the actual height now

warm plinth
#

The hight of the pyramid is 1/2 of the apothem of its triangles

runic beacon
#

wait i misunderstood the whole question

warm plinth
#

Oh xD

#

So the diagonal of the base of a quadriangular pyramid (not sure thats a word) is 18 * sqrt2 cm, the hight of said pyramid is half of the apothem of the pyramid's triangles, find the volume in exact values.

#

What i found is that the side of the base is 18cm, and that the triangle that forms using the apothem as a hypothenuse and the hight and half of the length of the base (9cm) as the cathetus' is a 30 60 90 triangle

#

Anyways i gtg

upper karma
warm plinth
magic lichen
#

guys how do i start trignometry?

#

whats the best place

#

to start learning trignometry

magic lichen
#

thx

#

damn bro 8th?

#

me too but im learning in 9th

#

i just came to 9th so im still 8th?

#

tries to make sure that i learn hard stuff in the earlier grades

#

yes yes

#

yeah just the basics not too deep into it

trim breach
warm plinth
#

ohhh thx

candid flume
#

how dis

#

Write the general form for all the solutions to cos0= -1/2;
based on the smaller angle.

I swear my prof didn't say anything about this s***t

simple rain
#

is anyone here

wise pawn
simple rain
#

how to do 10

wise pawn
#

I'd imagine it's a complete cone with the top chopped off, so you can find the volume of the whole cone and the volume of the piece cut out, and subtract it

simple rain
#

you have to use similar triangles but idk which

simple rain
#

of the full cone

coarse saddle
simple rain
#

can u tell me the sides for it

coarse saddle
#

I don't want to give you the answer

#

I want you to figure it out yourself

simple rain
#

how to set it up

coarse saddle
#

try to complete the cone

#

draw the lengths you need, etc.

simple rain
simple rain
#

i don’t tho

#

the teacher showed in class but i forgot

#

so like this

coarse saddle
#

that's good

#

you're very close

simple rain
coarse saddle
#

remember

#

you aren't looking for x

#

you're looking for the height

simple rain
#

oh height is 12

#

3-4-5

#

i think

#

ok thx i got it

coarse saddle
simple rain
#

noooooooo

coarse saddle
#

what's wrong?

simple rain
#

i got it wrong

#

it’s B somehow

coarse saddle
#

you see

#

the answer doesn't matter as much as the work

simple rain
#

what i do wrong tho

#

there might be mistake on the key

coarse saddle
#

probably just a calculation mistake

simple rain
#

can you try it and see what you get

coarse saddle
#

emm

#

sure

simple rain
#

ping me cuz ima close discord

coarse saddle
#

@simple rain did you forget to delete substract the volume of the smaller cone?

simple rain
#

what did you get as answer

#

ooohohh wait yea

#

oop

upper karma
#

hiii can anyone help me with this? it’s geometry snf it’s surface area of composite figures

lapis moon
#

divide and conquer: outer curved surface area is $2 \pi r h$

somber coyoteBOT
#

vin100

lapis moon
#

upper and lower surface area is circle's area minus that of the square

#

inner surface area is four times each rectangle $sh$, where $s$ is the side length of the square

somber coyoteBOT
#

vin100

lapis moon
#

it suffices to establish a relationship between $s$ and $r$.

somber coyoteBOT
#

vin100

lapis sequoia
#

i need help with something in my geomotry

deep niche
#

idk how to do this

vestal siren
#

can someone explain to me how to do this

wheat walrus
vestal siren
#

yes

#

I just don't understand the angle 0 part

wheat walrus
#

the “0” is called theta and it’s just a variable

#

same for x, y, z, or any other alphabetical letter

upper karma
#

can someone help me with 1 hw question?

#

yes? or no?

wheat walrus
#

depends

#

what is it

upper karma
#

geometry

#

circle

wheat walrus
#

send a picture !

#

oh circle

upper karma
#

circle

wheat walrus
#

ew

#

nah i don’t know this

#

and if i learned it, i’ve expelled it from my memory

upper karma
#

so no help?

wheat walrus
#

unfortunately

#

perhaps consult khan academy

upper karma
#

is there someone here who specializes on geom?

upper karma
wheat walrus
#

khan academy

upper karma
#

ive never used it

wheat walrus
#

search up the concept on google or youtube idk

upper karma
#

do i upload picture?

wheat walrus
#

no it just teaches you the basic concept

upper karma
#

dang ok

#

ill be back

wheat walrus
#

good luck

upper karma
#

ty

vestal siren
#

so the problem i had would be 55 right

#

or wrong

wheat walrus
#

what question are you referring to in the worksheet?

azure crown
upper karma
#

but im not sure if the angle is supposed to equal the bigger arc

#

i was absent a day and the teacher didnt teach me just gave me notes

azure crown
#

equation is angle = 1/2(151-45)

upper karma
#

why 1/2?

azure crown
#

thats the theorem

upper karma
#

i did —> angle= 151-45/2

azure crown
#

well that doesnt equal 53

#

unless u mean (151-45)/2

#

which is the same thing as mine

vestal siren
upper karma
#

oh yeah

plucky mantle
#

Can someone give me some tips for memorizing the unit circle? I've got an exam next Tuesday (pls ping me)

upper karma
#

whats the unit circle @plucky mantle

azure crown
#

then repeat until u can write the whole thing

upper karma
#

whats the unit circle duck?

#

is it in geometry?

azure crown
#

i didnt learn it yet

upper karma
#

u need to memorize this whole thing?

#

i would just print out a tiny version of it and place it in a pocket at that point ngl

azure crown
#

when do u learn that

upper karma
#

idk

wheat walrus
upper karma
#

i havent

azure crown
#

is that precalc or geometry

wheat walrus
#

@vestal siren when you’re finding the angle measures, use reverse sine, cosine, or tangent

#

don’t base the answer off of another angle measure you figured out in case your solving is inaccurate, stick with the information you’re given

vestal siren
#

ohhh

upper karma
#

Can someone help me with the vocab ?

  1. A (blank) is the set of all points in a plane, equidistant from a given point called the center.

  2. A (blank) is a segment whose endpoints are the center of the circle and a point on the circle.

  3. An angle whose vertex is at the center of the circle and whose sides intersect the circle is called is a (blank).

  4. A chord that contains the center is called a (blank).

warped atlas
upper karma
warped atlas
plucky mantle
#

It's used with radians

vestal siren
#

can someone check something for me

storm portal
north heart
vestal siren
#

okay so

#

i'm doing this problem and I'm confused

#

and i'm very confused for 3

wicked fossil
vestal siren
#

nvm i got it

wicked fossil
#

ok

opaque gull
opaque gull
#

To measure the angle

plucky mantle
#

Or the law of sines

opaque gull
#

That too

upper karma
opaque gull
#

Like 10th 11th grade

#

Somewhere there

#

At least we do here

upper karma
#

ok

opaque gull
#

u can read about it if ya want

tepid vault
#

help

#

is this valid for all integer p

#

$\forall p \in \mathbb{Z}$, $cos(2\pi p) = 1$ and $sin(2 \pi p) = 0$

#

yeah right?

#

just wanted to confirm cos me bad at trig

somber coyoteBOT
#

texaspb

gleaming nova
#

first one yes

wise pawn
#

second one yes

gleaming nova
#

second one could instead be sin(pi*p) = 0

tepid vault
#

okay

#

then

#

$cos(2\pi p + \theta) = sin(\theta)$?

somber coyoteBOT
#

texaspb

tepid vault
wise pawn
#

the fundamental thing to know is they both have a period of 2pi

#

so you can always add or subtract an integer multiple of 2pi from the argument

tepid vault
#

I wanted to check if $cos(2\pi p + \theta) = cos(\theta)$

somber coyoteBOT
#

texaspb

tepid vault
#

this is vewy important for me to understand a thing here

wise pawn
#

cos(x)=cos(x+2pi)

wise pawn
#

yw

tepid vault
#

because like

#

the guy did this

#

now i gotcha

mystic coral
#

What did i do wrong?

pure cape
#

what you did wrong is that you assumed the point was in the first quadrant

#

there isn't just one angle that satisfies tan(theta)=sqrt(3)

mystic coral
#

How do I find the other angles that works?

pure cape
#

try to solve the equation tan(theta)=sqrt(3) generally

#

and then choose the angle that would satisfy the following condition

mystic coral
#

Im not entirely sure how to go about that. I assume it would have to do with the range of trig functions?

#

So if my assumption is correct, then my other coordinate would be (5,-pi/3)?

pure cape
#

that's in the fourth quadrant, which is also not where the point lies

#

you can search further into this since i dont have a lot of time to explain, the equation tanx=a has the general solution x=arctan(a) + kpi where k is in Z

#

and then just restrict this to the interval [0, 2pi], and then choose the appropriate angle

mystic coral
#

Alright, ill look into it, thanks

ancient spoke
#

Can y’all help me on this

dark sparrow
#

do not ping everyone.

ancient spoke
#

My bad

lapis moon
#

sorry we're here to do your homework

dark sparrow
#

we're not here to do your homework.

ancient spoke
#

I said help

lapis moon
#

my bad +1

ancient spoke
#

Not do

dark sparrow
#

in any case

#

there are two parts to this problem

#

one about the length of BC, the other about the area of the whole thing

lapis moon
#

but we can give you some hints

#

i suppose

dark sparrow
#

which of these would you like help with

#

if both, which one first

ancient spoke
#

I’ve been stuck on this for an hour

dark sparrow
#

which of these would you like help with?
if both, which one first?

ancient spoke
#

I just need some tips

lapis moon
#

what? the question writer has spoonfed students with answer? sosad 😦

#

you're supposed to find the length, but he/she has just stated that

#

and ask for an explanation for that

dark sparrow
#

there are two parts to this question. would you like to get help with part a first or part b first?

#

ok

#

so look at the diagram

lapis moon
#

just use symetry

ancient spoke
#

Thanks much appreciated

dark sparrow
#

what are you thanking us for

#

i for one havent even started

#

i was gonna take you through it

ancient spoke
#

For youre time

lapis moon
#

upper & lower half symmetric

dark sparrow
#

do you want to continue?

lapis moon
#

left & right half also symmetric

#

so ...

ancient spoke
dark sparrow
#

ok

#

ok so you see how the shape is rectangular all throughout, yes?

#

so if you were to connect C and F with a straight line, it would be aligned with BC and FG

#

hence the line segments BC, CF and FG add up to the height of your shape, which is 20 as the diagram says

#

do you understand this

#

therefore

#

no

#

x is just x

#

it is just a number, and all your work will involve expressions in terms of x

#

the line segments BC, CF and FG add up to the height of your shape, which is 20 as the diagram says
do you understand this

#

what did i say?

#

did i say they were all 20 or did i say they added up to 20?

#

well that answers your own question now doesn't it

#

divide what by what?

#

...

#

ok you know what nevermind

ancient spoke
#

Thanks

#

I got it

mystic salmon
#

Hi, I asked this ques in a help channel, but I'll put it here as well since it is to do with trig

#

Question: I'm trying to simplify it and get it into terms of one trigonometric function

I know tan x = sin x / cos x
I also know that it is the same as: tan x * (1-sin^-2)^1/2
so I get to the stage tan x * (1-sin^-1 x)
but every step after this I get confused

#

could someone offer some guidance, thanks, ps please ping @ me if you reply 📐

slate kraken
# mystic salmon

Well...let me give u hint...sin^-2x means 1/sin^2 x....now we get within square root...1-1/sin^2 x ...again...there's the other formula of trigonometry...sin^2x+cos^2x =1 ..try and see if u can utilize these infos

wispy iris
#

hi, I was wondering if "sec = sin^-1" or if they're different. Thanks in advance.

grave pond
#

The notation sin^-1 is almost always used to denote the inverse function of sine, not for talking about 1/sin(x).

#

This is inconsistent with sin²(x) meaning (sin(x))², but that the convention we have, like it or not.

wispy iris
#

So, if I have the Adjacent and the θ of a triangle, but my calculator only has sin^-1, then "(sin^-1 θ) * Adjacent ≠ Hypotenuse"

grave pond
#

Yeah, definitely not the same thing.

#

And not just because sec is the recprocal of cosine rather than of sine.

#

Your calculator ought to have a way to type adjacent / cos(theta), though.

wispy iris
#

huge thanks

umbral radish
#

can anyone solve x for me?

dire hull
#

idk much but i do know theres the right angle which is 90

#

add 90 + 42

#

then substract by 180 to get your third angle

#

damn it says trig ratios

#

mb

umbral radish
#

all good

reef oxide
#

Use a tangent with 42°

reef oxide
umbral radish
#

I really don't understand, im sorry

wicked fossil
#

Tan(angle)=opposite/adjacent

#

What side is opposite from 42?

#

What side is adjacent?

reef oxide
#

That's okay! We're solving for x, and given an angle of 42° and a length of 5. If we can put these 3 terms in one equation, we can find their values relative to each other.

Since this is a right triangle, we can use the trig ratios to set that equation up.

From the angle of 42, we have the hypotenuse above it and the adjacent side, 5 below it. To it's left, we have the opposite side, x.

The tangent of this angle is equal to the ratio of the opposite side over the adjacent side.
tan(x) = opposite/adjacent
tan(42) = x/5

Multiply both sides by 5.
(Move the 5 to the other side while observing sign rules, that's how I think about it)
5*tan(42) = x

Punch the left side of the equation into a calculator, round to the nearest tenth as the question asks, and that's your answer.

#

Phew

opaque gull
#

@umbral radish

upper karma
#

Hello

opaque gull
#

hey

upper karma
#

I have normalized coordinates from -1.0 to 1.0 for X and -1.0 to 1.0 for Y
-1.0 X is left, 1.0 X is right, -1.0 Y is down, 1.0 Y is up. I want the center of an euqilateral triangle to be on 0.0, 0.0, the lower left point to be on -0.5, 0.0 and the lower right point to be on 0.5, 0.0
Which one of these methods best represent the center of the triangle in this case?

#

My idea was to get the height of the triangle whichs is sqrt(0.75), to divide it by 2 for the Y position of the upper point and have the negative value (-sqrt(0.75)/2) for the lower points

#

this is the result of that

#

and these are the coordinates I chose

#

Another person used these coordinates

#

which had this result

#

And says that his triangle in the center

#

Does anyone know which one is actually in the center?

#

Btw the triangle is equilateral

magic lichen
magic lichen
wispy iris
upper karma
#

A = 3

#

Segment AC = 3 SQRT 2?

#

D

#

AB = AC multiplied by SQRT 2

#

AB = 3 SQRT 6

hazy holly
#

Hey. I'm trying to solve this problem. I drew the radii and prepared the triangle shown. I found that $r = \dfrac{3a}{8}$. I've tried using trigonometry in different ways and I keep finding that $x = \dfrac{18a}{25} = 0.72a$, but the answer says $0.6a$. This is not homework, this is problem 206 from Solving Problems in Geometry by V. Gusev, V. Litvinenko and A. Mordkovich.

somber coyoteBOT
#

EvilSonidow

terse breach
#

I need some help

#

I need to figure out the height of the tripets

sleek mirage
#

can someone show me how to get the answer for this or point me in the right way?

hazy holly
somber coyoteBOT
#

EvilSonidow

hazy holly
hazy holly
terse breach
#

I've used pythagoras theorem to calculate the side and the area of the first two triangles, but the third one is missing it's height

sleek mirage
hazy holly
#

Do you mean x or did you substitute back to find the angles?

#

It asks for the measure of the angles

sleek mirage
#

Both

#

I didnt get the right x value or the angle measures

hazy holly
#

What x did you find?

sleek mirage
#

like 7.07...

#

the answer is x=5 and m<dec =48

hazy holly
#

The equation is $2x^2 -2 = 10x-2$, where did you go from here?

terse breach
#

Basically, I've found the area of the first triangle, but now I need to find the area of the last angle in order to sum it up and get the area

somber coyoteBOT
#

EvilSonidow

sleek mirage
hazy holly
sleek mirage
#

no wait first i factored out the 2

hazy holly
#

$$\begin{aligned} 2x^2 -2 & = 10x - 2 \ 2x^2 & = 10 x \ x^2 & = 5x \ x^2 -5x & = 0 \ x(x-5) & = 0 \ x & = 0 \ x & = 5 \end{aligned}$$

somber coyoteBOT
#

EvilSonidow

hazy holly
#

Naturally $x=0$ doesn't make sense.

somber coyoteBOT
#

EvilSonidow

hazy holly
sleek mirage
#

that makes a lot of sense actually i see what i did wrong

#

thank you!

terse breach
hazy holly
hazy holly
terse breach
hazy holly
#

No, like this:

#

Crude drawing but you get it. Use right triangle trigonometry to find height AE and therefore find the area

terse breach
hazy holly
#

Geogebra

#

Online and free

terse breach
hazy holly
#

Exactly

terse breach
hazy holly
#

Doesn't matter, you don't need it for the area

terse breach
#

Really? So it's not included in the area?

hazy holly
#

No. You would need it for perimeter, but since it's area you don't need the length

#

Do you know the area formula for a trapezium?

terse breach
#

then it's all simple, base times height

hazy holly
#

That's for a rectangle, not a trapezium

terse breach
hazy holly
#

No, there are not

#

At least there are not 4 congruent right triangles

#

You are very close but you're using the wrong formula

terse breach
#

the area will be the sum of the two pararells, then divided by two and multiplied by the height

hazy holly
#

Yes

terse breach
#

Alright, thank yoy for the info

#

It's my first time calculating the area for a trapezium

#

our school doesn't go through it, I have to get maths from the internet

untold tundra
#

so i just post my question here

#

?

dire hull
#

Yes

cerulean shell
#

how do i do this?? what does this even mean

grave pond
#

Knowing "cot theta is undefined" and "theta is between pi/2 and 3pi/2" allows you to deduce exactly which number theta is.

lofty depot
trim breach
#

Is this an exam?

lofty depot
#

Naw it’s not

trim breach
#

Do you know the formula for arc length?

lofty depot
#

No what is it

trim breach
#

,,2πr(θ/360)

somber coyoteBOT
trim breach
#

There we go.

lofty depot
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Aii what’s next

trim breach
#

You have a radius, r, and an angle measure, θ.

#

You can just plug them into the formula.

sleek mirage
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Idk where to start with this problem

dark sparrow
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do you know what standard form is for equations of circles?

gray hull
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Here's the question, let me get my work.

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At first, I thought the areas of these were related but I'm pretty sure they're not. I would say something about trying to relate the lines which bisect these angles, but yeah I don't know how to prove that they go through the centroid of WXYZ.

sweet whale
runic beacon
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@sweet whale go to an available math help

sweet whale
#

what?

runic beacon
wicked dagger
sweet whale
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oh nvm

wicked dagger
#

its a right triangle, so you can use the pythagorean theorem to find the third length

tulip vector
#

help me pls

upper karma
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180 - (19x+3) + 6x + 15 + 9x + 16 = 180

upper karma
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guys

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help me

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prove pytagoras' law

trim breach
# upper karma prove pytagoras' law

There are a ton of resources covering the proof. You might want to start with a Google search unless there is something specific you don’t understand.

lost sable
#

Anybody know of any cheat sheets for all conic sections?

steady jetty
#

Can someone help me with the top equation, I’m kind of confused what identities to use to deduct sin(x+y)/cosxsiny to 1+cotxtany

wheat steeple
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I mean, you've already completely 90% of the solution

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if it helps, split the numerator and distribute and denominator

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side note, the denominator must be given as sinxcosy

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or else the identity is wrong

steady jetty
#

Hmm

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I’m still kind of confused is it possible if you can write it out

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Because after I cross out the denominator I’m stuck and can’t relate back the the other side of the equation

opaque gull
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Whats the goal here?

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Solve for y? For x?

steady jetty
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Prove that both sides of the equation r equal

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Using trig identities

opaque gull
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Ohhhh ok lemme just eat dinner

opaque gull
steady jetty
#

Never mind I got it

lapis moon
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$${\overrightarrow {AD}}={\frac {|{\overrightarrow {CD}}|}{|{\overrightarrow {BC}}|}}{\overrightarrow {AB}}+{\frac {|{\overrightarrow {BD}}|}{|{\overrightarrow {BC}}|}}{\overrightarrow {AC}}$$

somber coyoteBOT
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vin100

grave pond
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I'd call it something like convex interpolation, but that's not an already established name.

tepid cave
opaque gull
#

A circle tangents the line 3x-4y=0 at the point (8,6) what's the midpoint of the circle? It also intersects the positive x-axis

I solved it to y=(3/4)x and chose origo (0,0) then found the midpoint between the points I got (4;3) is that right?

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I feel like it's too good to be true and a much harder process

nocturne remnant
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You mean the centre of the circle?

dark sparrow
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"tangent" is not a verb by the way

wise pawn
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a circle constructed with its center at (4,3) will be cut in half by the line, so it can't be tangent to it

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also it's not gonna be unique if it only intersects the positive x-axis, since there are many circles that are tangent to the line and intersect the positive x-axis, but it would be unique if it was required to be tangent to the x-axis

opaque gull
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I guess intersects?