#geometry-and-trigonometry

1 messages · Page 11 of 1

blissful spire
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Right?

thin locust
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yes

blissful spire
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Cause the circles area would be pi r squared

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Which is 25pi

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Ok Tysm

thin locust
#

ye

upper karma
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Area of the Circle= pi r^2= pi*5^2 which is approx. 78.53982 (round it accordingly)

blissful spire
#

I think it’s just asking for the exact answer so I can keep it in pi form

upper karma
#

alr!

bronze sand
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in a rectangle, the base is twice as long as the height. calculate the area of the rectangle if the diagonal is √215 cm.

Can someone tell me how to solve this question??

nocturne remnant
#

represent the base and height in terms of the same variable

wind coral
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Use Pythagoras to determine x

upper karma
#

what do they mean by this

dry atlas
limpid onyx
#

Prove CU x CV=DU x DV where U and V are the circumcenters of AOC and BOD respectively

cold chasm
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is there some sort of list for theorems abt circles

wind coral
cold chasm
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i was told there was 14

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i can send a list but i need help proving them

wind coral
#

Oh ok, I can't help prove them sty

cold chasm
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its ok

visual ermine
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Guys so like if I'm evaluating functions and like it gets to cos(-1) like then what

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Cus tbh my trig is not great and like I just keep getting messy decimals and no good values or anything

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Unless I'm being really dumb and it's pi but I'm pretty sure that's not how trig works

south pawn
#

could somebody help

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<@&286206848099549185>

foggy parcel
wicked narwhal
#

@south pawn

dull seal
rough stratus
#

hi

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@rough stratus hi

river blaze
#

Find X?

river blaze
lapis wind
#

help pls

pallid vine
# lapis wind help pls

Start off with y= tan x
You can see that the graph is translated pi/4 to the right first, so we now have y = tan (x - pi/4).
From here, we check for at least one point:
E.g. when x = pi/2, the y-coordinate should be 3. As tan (pi/2 - pi/4) = 1, we need to multiply this equation by three to stretch it parallel to the y-axis, and get the desired equation y = 3 tan (x-pi/4)

upper karma
#

"Prove that if a plane is perpendicular to two secant planes, then it is
perpendicular to the intersection of these planes."

help pls

floral shale
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You can try doing the cross product of the planes' normal vectors first

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Not entirely sure but that's something you could try

upper karma
#

hello. im not sure if i can post this question because its in calculus. but basically im trying to solve a question that deals with arctan and the limit as "a" is approaching -infinity of arctan(a). should i look at the tan(x)'s domain to justify the behavior of arctan?

pallid vine
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Seems like a reasonable step, but just be careful to justify, since tan(x) has the domain over all the reals, whereas the domain of tan(x) is restricted to define arctan(x) as a function, such that it's range is (-pi/2, pi/2).
Since we're in geometry chat, you could also consider, if you had a right-angled triangle, and one of the acute angles has fixed adjacent side, but an opposite side which has its length approaching infinity...
Seems kind of wishy washy, but it seems like as if the angle gets closer to pi/2.

upper karma
pallid vine
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That would probably be fine, so long as you keep domains/ranges clear for each function, and don't get mixed up between the two :)

granite sparrow
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Hi

#

I need some help

  1. Prove that
    (Sinx + Cosx )² + (Sinx - Cosx )²x = 2
fallow sable
#

Can someone explain the operations on deriving half angle identifies from the Euler formula

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my tutor showed me the formula for if I forgot my identities

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I kinda forgot how he even started it 🥲

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I’m in precalc 2 btw if that’s necessary information

verbal jacinth
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What is the given informations

nocturne remnant
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There are at least 9 things named “Euler’s formula”opencry

spiral mesa
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You may want to look at this too

warm canopy
upper karma
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I think the sum is 180 degrees

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You just have a star right ?

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a random pentagram with nothing specified

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lemme try

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Lemme upload pic

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@warm canopy

warm canopy
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thank you!!

upper karma
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no problem

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Glad to help

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Now I disappear into the shadows once more ...

nocturne remnant
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...you literally asked them if it was asking for angle sum and it wasnt tho

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tho honestly that's the only reasonable thing that would be asked

wraith mirage
warm canopy
# upper karma

wait which angle is which and where did the A’ B’ C’ D’ E’ come from are those the interior angles of the polygons

upper karma
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Yes

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I wrote it in a quick way

half eagle
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how do i solve this?

grave pond
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Doesn't your textbook explain how to find the distance between points in a coordinate system?

half eagle
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it does

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i think'

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but i dont have it on me rn

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soo

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its a formula

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but i didnt memorise it

grave pond
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You might have to rederive it, then. Draw a hoizontal line through one of the points and a vertical line though the other. Together with the line connecting your two points, they form a triangle with one right angle. Apply the most famous theorem about right triangles you remember.

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... or you could also use what Daht posted and lose the learning opportunity.

flat owl
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My bad

timid thistle
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is there things like

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uh

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like you have $\sin \theta = \frac{a}{b}$ and then $\sin^2 \theta = \frac{a^2}{b^2}$, is there such a thing as eg. $\arcsin^2$?

somber coyoteBOT
grave pond
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There's not a particular name for it, no.

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In some situations it can be useful to know that (by trigonometric identities about squared sines) we do have $$\sin^{-1}\sqrt x = \frac{cos^{-1}(1-2x)}{2}$$

somber coyoteBOT
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Troposphere

timber cargo
smoky jetty
pliant pumice
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Hello! I have a question about proofs. I learned that proofs are usually written using table of statements and reasons, and every small step should have a reason (name of some property, not just explanation). I find this way very long and exhausting. Are there other ways to write proofs and solutions in geometry?

dark sparrow
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you learned that 2-col proofs were the "usual" format?

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cause yeah thats bureaucratic as shit and tiring to stick to

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usually a porof is just plain-english prose maybe interspersed with some calculation

pliant pumice
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So usual "non-bureaucratic" proof is just explanations in words and some calculations when needed?

dark sparrow
#

yes, essentially.

silent plank
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two col is excessive in the need to explicitly state "given" and trivial theorems

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which yeh, can be exhausting, there's no real need to have all that

grave pond
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I think "two-column" proofs could make some sense if they were taught as a scratchwork technique for making sure you have all your ducks in a row before you start writing out the human-readable proof. But they're likely harmful if they become a homework objective in and of themselves.

pliant pumice
#

Thanks!

dire mortar
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yo hello can anyone help with my homework? trig

upper karma
#

@everyone does anyone know about pythagoras theorem?

grave pond
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Nobody knows about Pythagoras' theorem; the last surviving description of it was lost when the Great Library of Alexandria was sacked.

upper karma
timber cargo
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Okay

upper karma
#

how do I know if my foci is parallel to the y-axis or the x-axis?

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im wondering if its related to the semi-major, but im not quite certain

grave pond
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The foci of an allipse always lie on the major axis.

devout warren
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is there any reasoning behind this being ex. sin(v+pi) and not sin(v ±pi)?

upper karma
#

since semimajor = the a component

tender token
# upper karma ok, where **a** is greatest, that's where the focal is?

So I'm assuming you're asking about the focal point of an ellipse, which is one of the two points that define the major axis of the ellipse.

In an ellipse, the distance between the center and each of the two foci is denoted by c, and the distance between the center and each vertex (i.e., the endpoints of the major axis) is denoted by a. The semi-major axis of the ellipse is then given by a, and the semi-minor axis is given by b, where b = sqrt(a^2 - c^2).

So to answer your question, no, the location of the focal point(s) is not determined solely by the value of a. The location of the focal point(s) depends on the values of both a and c, as well as the position and orientation of the ellipse.

However, it is true that the value of a is related to the length of the major axis of the ellipse, and therefore to the distance between the two vertices. Specifically, the length of the major axis is given by 2a.

upper karma
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@tender token

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is it just the semimajor that decides?

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sorry if im asking the same thing after you explained but i dont really understand ellipses

tender token
#

What would the points of my own geometrical algebra equation be? I used such 2 + 2 = 2x (squared (2)) which both sides of a square is 2 it converts into a cube which is entered into cube = 2x (squared (2))?

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Summary: Square (both sides are 2) = 2x² = Cube 2x²

median igloo
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My whole class strugglin need som help

foggy parcel
#

26 should be 22.83 the value of DE

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26 no. Ques ans: 22.83

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@median igloo

dark sparrow
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!nosols

lime crownBOT
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As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.

snow tide
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"find the length of the unknown sides of this right trapezoid, and find the area of the trapezoid"

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im struggling with this problem

austere light
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not sure what i did wrong here, deltamath says im wrong

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nevermind i figured it out

abstract dagger
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👌

copper lark
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I need help

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Can u do this question

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Help

#

Ignore the writing around it can you help with that question tho

lofty tangle
lofty tangle
lofty tangle
grave pond
#

I've drawn a few more lines -- red is horizontal and green is parallel to the inclined plane so the angle between red and green is the angle of the ramp.

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Now red is perpendicular to black, and green is perpendicular to dashed blue.

smoky jetty
grand heron
graceful quest
#

b

timid thistle
grand heron
grand heron
smoky jetty
#

you may also use law sine for the oblique trianglge

foggy parcel
#

Ups here B & C are the centre of the two circles

#

Since radius 2
AB = BC = AC = 2
so according to the tringle being equilateral
angleABC = angleACB = angleBAC = 60degrees

so [ABC circular cut] = theta/360 * pier^2
= 60/360 pie * 2^2
= 1/6 * pie * 4
= 2pie/3

and [tringleABC] = rootover3 a^2/4
= rootover3 * 4/4
= rootover 3

so [black region under ABC circular cut] = 2pie/3 - rootover 3
= 2pie - 3rootover3/3

So the other one is also 2pie - 3rootover3/3

And the down black region can be divided with the tringle where it creates the same situation like the upper one

So there should be 2 other black region under circular cut with same area

So all black regions under circular cut are 4
[all black regions under circular cut] = 4{(2pie - 3rootover3)/3}
= 8pie - 12rootover3/3

And the other same tringle (with same area) should also be added as the down black region except the 2 down black regions under circular cut

So the actual [black region] = 8pie - 12rootover3/3 +root3
= 8pie -12rootover3 + 3rootover3/3
= 8pie - 9rootover3/3
Hence,
8pie - 9rootover3 / 3 = apie - b rootover c/d

a = 8
b = 9
c = 3
d = 3

and gcd{8,9,3,3} = 1

              So     ( a + b + c + d)   =  8 + 9 + 3 +3 
                                                    = 23
                                                     {Ans?)

Am I right or not?

#

<@&286206848099549185>

foggy parcel
dense galleon
#

Isn’t ABC triangle equilateral

foggy parcel
#

Yea

foggy parcel
chrome timber
#

Hey anyone here studies Euclidean geometry

grand heron
reef frigate
#

obc is 50 because ob bisects ac. so obc is 50 so u know bac. ob = oa so z = 50 - bac.

split grail
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aob = 180 - oba - oab = 180 - 2*50 = 80;

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bac + bca + abc = 180 ==> bac = (180 - abc )/2 ==> bac = 40

upper karma
#

hello. just a question, is the definition of horizontal tranverse axis means that the parabola opens upwards and down?

graceful idol
#

can anyone help me with this one, i thought the answer was 82 but i guess not

upper karma
#

OMG I'M LEARNING THIS, TOO

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SOO FRIKIN HARD+EASY LMAO

#

just use this formula... m<1=(m of arc AB + m of arc CD)
(These are just random letters, you can do it accordingly for your problem)

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he left oml

upper karma
upper karma
#

hello guys, i have a question. Idk if this is basic or advanced math too so i ask here

#

i saw this guys calculate circumcircle of a given triangle's coordinates with something called D. I have no idea what that is and how do this work

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you may confuse by coding, but at the end he give result of the triangle circumcircle coordinate is:
(X / D, Y / D)

grand cargo
#

Hi, can someone help me with this one? We're supposed to find the area for the ones that are shaded.

upper karma
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and reversed the formular

upper karma
grand cargo
#

Ah

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So x= 7 and y=5?

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Wait nvm I don't think it's like that 💀

upper karma
#

i dont really remember any formula from high school, but there would be something to do with the angle

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if you have 1 angle and 2 edge, you can calculate the other edge

grand cargo
#

Huh

upper karma
#

you apply that formula to both triangle, you will have an equation

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solve that equation you will have the answer

grand cargo
#

does that only applies for right triangles or not?

upper karma
#

no, obs not

grand cargo
#

The angle is unknown in the problem however

upper karma
#

that is why we need the equation

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if you notice closer, sum of that 2 angle is 180

grand cargo
#

Wait which one

upper karma
#

well, seem like everything is obvious when youre asian haha

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the one in middle

grand cargo
#

💀

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Huh

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Still trying to figure it out

upper karma
#

you see it now?

#

what is 360 - 90 - 90?

grand cargo
#

180

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Ok yeah I see it now

grand cargo
#

Wait how do we find the 2 angles though, they clearly don't make a 90°

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And how do we find the area after that 💀

nocturne remnant
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just use it on each triangle and hope that stuff cancel

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A solution without trigonometry probably exists but is not very easy to find

grand cargo
#

e

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I was thinking about using that but the angle is unknown

nocturne remnant
#

The angles are supplementary; their cosines sum to 0

grand cargo
#

Huh

nocturne remnant
#

Fyi I was talking about this

grand cargo
#

Ah

worldly tundra
#

im confused an what nEZ does

exotic yarrow
somber coyoteBOT
#

Civil Service Pigeon

exotic yarrow
#

It’s because you need to add integer multiples of the period

#

Cause otherwise, you could say stuff like $\sin(\pi/2)=\sin(\pi)$, which is clearly false.

somber coyoteBOT
#

Civil Service Pigeon

worldly tundra
#

ty!

astral viper
exotic yarrow
astral viper
#

Yes

#

Ok

#

What’s m

#

=

exotic yarrow
timber cargo
#

Such a tall building with only 3 floors

worldly tundra
#

what i did so far was made 3x=a and then said 10(2sinacosa)=0

#

but im not sure where to go from there

gaunt path
#

How do I find x

timber cargo
gaunt path
#

Ik sin cosine and tangent and law of sine and law of cosine but I forgot how to implement the law of sine and cosine

#

law of sine right

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since its an enclosed angle

timber cargo
#

For this problem it's more convenient to use tangent

#

You are given a side length that is opposite of the angle and adjacent to the angle

#

So, you'll have to use tan^-1 (30/8) to get the angle

gaunt path
#

ohhhhh

#

ok thank you that makes sense

#

I forgot abt the inverse ones

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I was trying to write 8tan(x)=30

#

so 75.07 deg?

timber cargo
#

If they ask you to round to the nearest hundreds, then yes

blissful spire
#

Is there a clear formula to calculate volume?

#

Sry it was just unclear for me

#

Nvm sry got it

timber cargo
shy sun
#

Not really sure how to explain this. I have a line to a point and a 3d vector from that point with an X and Y rotation. How can I find the angle between the line and the vector?

gilded topaz
#

Can someone please tell me if 13 is right

#

I think I did it wrong but idk how else to do it😭

#

guys?

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pls

nocturne remnant
#

i think arc YVU stands for the arc that starts from Y and goes counterclockwise around the circle until meeting U

lethal fable
#

how to do this

#

😭

#

please help

hexed shale
#

are you trying to find the hypotnuse

lethal fable
#

yes

timber cargo
lethal fable
#

😭

#

What the formula I dont have my notes

half iron
upper karma
neat plank
proven badger
#

Need help with these questions (last three especially) Thanks!!

agile oyster
smoky jetty
#

You may also refer to Heron's formula as 3 sides are also given

#

use calculator for convenience

dire snow
#

How do I prove that in a triangle the semi perimeter is always bigger than a side?

silent plank
#

a late?

dire snow
#

A side?

#

I think you call it side

silent plank
#

what have you tried?

dire snow
#

This

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Maybe I have to subtract ab and bc in every part

void charm
dire snow
#

Yeah I mean that

silent plank
#

use lowercase notation instead of segment notation,
it'd be much easier to read

dire snow
#

?

void charm
#

whats the equation?

dire snow
#

Wdym

#

It's here

void charm
#

brb

dire snow
#

Oki

silent plank
#

instead of triangle inequality, you can use something like
a <= b<= c

#

wlog

dire snow
#

Uhm

#

No I don't know i know only this

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Btw

silent plank
#

its just basically sorting the lengths in order for convenience

dire snow
#

Is it fine if I subtract two egual sides in every part?

dire snow
#

But I can try it

#

Then I have to do another thing

#

It asks me another thing

silent plank
#

and apply that to get more info about
s = (a+b+c)/2

dire snow
void charm
#

backk

silent plank
#

well your inequalities are just saying that double the perimeter is greater than the perimeter

#

which is trivially true

void charm
#

can u tell me the equation?

dire snow
#

What equation pt2

#

Xd

void charm
#

lmao

#

i mean the question!

#

that u wanna solve

void charm
#

let me think ;-;

#

The sum of any two sides in a triangle is greater than the third side.

Let a b and c be the length of the three sides

So we have (a+b) >c

Adding c to both sides we bave

a+b+c > 2c

This implies (a+b+c)/2 > c

The LHS is semi- perimeter of a triangle.

So semi- perimeter of a triangle is greater than any side of the triangle.

dire snow
#

Lmao you are a computer to write this in a second

void charm
#

its basically like

silent plank
#

consider given
a <= b
then
if a = k
you can conclude that
b >= k

void charm
#

b+c>a

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or like

#

a+b+c>2a

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that is

dire snow
#

Okk

#

Thx now I get it

void charm
#

(a+b+c)/2>a

#

then

silent plank
#

did you want greater than at least one side, or the longest side

void charm
#

a+b+c/2>b

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and

dire snow
#

Then I have to find how the semi perimeter is more long that the height

#

I try

void charm
#

(a+b+c)/2 >c

#

did u get it

#

;-;

dire snow
#

Yeah

#

Thx

void charm
#

yeh

#

np :)

#

what grade are u in rn?

dire snow
#

I try to do the other part

dire snow
void charm
#

?

dire snow
#

Let me check

void charm
#

huh?

#

i asked what grade like 9th grade 10th grade and stuff ;-;

dire snow
#

I'm Italian we don't have grade lmao

void charm
#

oh

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i didnt know

#

what year?

dire snow
#

Year 11 for Uk

void charm
#

oh

#

okay

dire snow
#

I looked only my age lol

void charm
#

so like how old are u

#

wait i have this equation

dire snow
void charm
#

ohk

#

do u know the formula of finding CSA of a cylinder

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wait i forgot-

dire snow
#

What is csa

void charm
#

curved surface area?

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LSA and TSA

#

um?

dire snow
#

Oh

void charm
#

yeh

dire snow
#

We did the last year

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Perimeter *height?

void charm
#

yehh im 14 rn so yeh

#

wrong

dire snow
#

What is a curved surface area lol

#

No we didn't do it

void charm
#

2 pie r h

dire snow
#

Didn't do it yeah

void charm
#

lateral surface area?

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total surface area?

#

u didnt do it?

dire snow
#

For lateral you mean all the area without counting the bases right?

void charm
#

yeh

#

tsa is with bases

dire snow
#

Oh k I did it

void charm
#

yehh

#

lol

#

do u remember statistics?

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ig u do have it now also

dire snow
#

I mean

#

Area*height

void charm
#

yeh ;-;

dire snow
void charm
#

mean,median and tsuff

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stuff*

dire snow
#

Not probability bcs I can't do nothing

dire snow
void charm
dire snow
#

Btw I can't do the other part

void charm
#

which one?

dire snow
#

How do I prove that in a triangle the semi perimeter is always bigger than the height ?

void charm
#

uh wait

dire snow
#

I try it too

void charm
#

i thought u understood?

dire snow
#

Oh got it

void charm
#

;-;

dire snow
#

It's the height now

void charm
#

ohh

#

the height

dire snow
#

I let you see if my think is good

#

Wait

void charm
#

yeah idk

#

ask someone from ur class

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if they know it

dire snow
void charm
#

i seeeeee

#

noicee

dire snow
#

Yeah lesgo

void charm
#

goodjob

dire snow
#

I have mainly to start thinking on what it asks

#

I have another exercise I will see if I have problems

void charm
#

okay

#

whens ur finals?

dire snow
#

Thx for the help again

void charm
#

ur final exams?

void charm
dire snow
#

You mean to graduate to university?

void charm
#

yeh

dire snow
#

I have to do another 4 years

void charm
#

ohhh okay

#

cool

dire snow
#

So basically I go to university at 18 years

void charm
#

yeah i got it

#

ur 15 now

#

so yeah

#

3 or 4

#

more yrs

dire snow
#

Yup

void charm
#

are u good at bio?

#

if u are explai types of animal tissues

dire snow
#

Maybe I think we have done like a melting pot of science in the last years ahaha

dire snow
#

Ok Lmao I didn't do tissues

void charm
#

tell me more about mole concept in chem

dire snow
#

I've thought you were referring of animals in general 💀

void charm
#

is it me or is it u?

#

being dumb rn

dire snow
#

Me that I don't read

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Lmao

void charm
#

help!

#

im so bad in bio

#

fr

#

i lost like 4 marks

#

forgot

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we shouldnt curse

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;-;

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and the assertion and reason ong 💀

dire snow
#

We've only did muscular and nervous but in general we didn't do biology. I can help you more in astronomy and chemistry

void charm
#

yeh chem

dire snow
#

We've only studied the human body

void charm
#

oh

#

okay

#

and the compounds atomic mass

dire snow
#

Lmao at 14 you've already did these things? 💀

void charm
#

i have just memorised first 20 elements in the periodic table

void charm
dire snow
void charm
#

yeh

dire snow
#

We'll doing these things the next year

void charm
#

u fr rn?

#

what the freak

#

then why do i have these

dire snow
#

Lmao

void charm
#

i finished it

#

and then suspensions and colloids

dire snow
#

It's because the schools in the world aren't the same

void charm
#

homogeneous and heterogeneous mixtures!

#

those are the easiest

dire snow
#

Yeah we are here

void charm
#

yehh

#

so tell me what do u understand by it

#

homogeneous has like solutions

#

and heterogeneous is of 2 types

#

colloids and suspensions

#

have u studied about saturated ,un saturated and super saturated solutions?

dire snow
dire snow
#

Satured is like when you can't dissolve anything else

void charm
#

do u want me to give u a brief about it

#

so u can answer confidently in ur class when the q comes!

dire snow
#

Lmao we are i the geometry part btw

void charm
#

oh okay

#

so u want me to or not?

dire snow
#

Yeah but maybe not here

#

I didn't see it

void charm
dire snow
#

That we are in this channel

void charm
#

oh yeah

#

so where?

dire snow
#

Where do you want but I will have to study astronomy and chimics for tomorrow test

void charm
#

or science

foggy parcel
dire snow
#

You can say it and I will see when I can

dire snow
foggy parcel
dire snow
#

Ok goodbye and thanks everyone

foggy parcel
#

Then why r u doin maths go study that topics xD

dire snow
void charm
dire snow
#

I have even to do Olympics of Italian then 💀

void charm
dire snow
#

At least it's for Monday (the Olympics)

dreamy cave
#

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

this is correct?

dark sparrow
#

yes

dreamy cave
sudden marlin
#

Can someone help me with this?

timber cargo
#

You know that a circle is 360 degrees

#

and 98 degrees is 40.62 in^2 in area

#

so make a proportion

sudden marlin
#

Ah, I get it, Thx

upper karma
#

can i get help on this (both perimeter and area)

wind coral
upper karma
#

ok

wind coral
#

after you do so, find the perimeter by adding all of the side lengths together

upper karma
#

are these correct?

mighty sparrow
#

Yes

cedar grotto
#

can the unit circle be used if the hypotenuse of a triangle is not 1

mighty sparrow
#

No because the unit circle has a radius of 1

cedar grotto
#

so whats the point of it then

#

if it can only be used with a triangle that has a hypotenuse of one

mighty sparrow
#

Because the hypotenus = sqtrt(cos(x)²+sin(x)²)

#

You have a triangle defined by sinus and cosinus

cedar grotto
#

what does that mean

#

you can use it with a traingle that has a hpyotenuse of anything?

mighty sparrow
#

I don't understand

cedar grotto
#

i dont understand what you are saying

#

i think my stupidity has confused you and me

mighty sparrow
#

If you take a point on the unit circle it is defined by a cosinus and sinus which bot have a value between -1 and 1 and if you use the pythagoras theorem with cos(x) and sin(x) you get the radius of the circle

#

So if you have a cosine you can get it's related sinuses

#

Thanks to the pythagoras theorem

cedar grotto
#

what is a cosinus

mighty sparrow
#

Cos(x)

cedar grotto
#

x is theta right

mighty sparrow
#

Yes the angle

cedar grotto
#

ok so let me get this correct because i have a very basic understanding of the unit circle

#

the unit circle is used to find the x and y of a triangle when you have the angle right?

#

like sin is y and cos is x

mighty sparrow
#

Yes

cedar grotto
#

so i just dont understand how it can be very useful if you can only use it to find the x and y values of a triangle where the hypotenuse is 1

#

unless im wrong about that

mighty sparrow
#

With a cosine you can find a sinus and vice-versa because the hypotenus is always 1 it's easy

cedar grotto
#

ok but im still not understanding

mighty sparrow
#

What are you not understanding?

cedar grotto
#

like what if the hypotenuse of my triangle is 34

mighty sparrow
#

Then you don't use the unit circle

cedar grotto
#

but then why even use the unit circle

mighty sparrow
#

Because in trigonometry you have a circle and a triangle that are alike

cedar grotto
#

so what im not understanding about this is the 1 being the hypotenuse

mighty sparrow
#

I guess

pale snow
# cedar grotto like what if the hypotenuse of my triangle is 34

It has nothing to do with that. The unit circle has a radius of 1 unit because it is easier to work that way but you can really have ANY MEASURE OF RADIUS. Since, in reality, there the concept of RADIANS is at stake (which has to do with the relationship of a radius and the perimeter of the circumference). That said, those RADIANS are used to measure an angle (counterclockwise, from the x axis).

That angle determines a point on the circumference (in any of the four quadrants) and from there the cosine (abscissa of the point on the circumference) and the sine (the ordinate of the point) are defined.

cedar grotto
#

i know why it is 1 because its the UNIT circle and 1 radian but im not getting why its that useful if you can only use it for a triangle with 1 as the hypotenuse

cedar grotto
mighty sparrow
#

I don't think so

cedar grotto
#

but he said " but you can really have ANY MEASURE OF RADIUS. "

limpid condor
#

does e=mc2?

mighty sparrow
#

He said that it's easier to use 1 as a radius but you could tweak it to have any radius

cedar grotto
#

yeah so why did u say i dont think so when the hypotenuse is the radius

#

and how would you tweak it to use and radius and therefore any hypotenuse

mighty sparrow
#

Because i personaly didn't learn any purporse for a unit circle to have a different radius than 1

mighty sparrow
timber cargo
cedar grotto
pale snow
upper karma
#

are these correct

silent plank
#

perimeters are wrong

sand matrix
# cedar grotto i know why it is 1 because its the UNIT circle and 1 radian but im not getting w...

It is valid for all triangles. Remember that sinx and cosx are periodic functions which means they repeat values on a certain interval.

Think about a simple value like sin(30*), this evaluates to some ratio which is 1/2. Now let's use your aforementioned example of a hypotenuse of 37. By using the unit circle we know that a value of 30 degrees or pi/6 radians evaluates to 1/2 and this can be applied to any triangle.

Let's say that your triangle has sin(x) = 37/74, we know that x = pi/6 works because of the unit circle.

#

I hope this makes more sense @cedar grotto

frail ridge
#

This might be a dumb question, but how do you draw a triangle given it's name (∆abc for example) ?

#

And is ∆abc and ∆cab the same triangle or is it different?

silent plank
#

usually capitals should be used for points

#

triangle ABC, is just a triangle with points,vertices A,B,C

#

you can have your A,B,C clockwise or anticlockwise, doesn't matter

frail ridge
#

But it's still in some form of order

#

Right?

silent plank
#

well for a triangle it doesn't matter, it'll be in order no matter which way you arrange them

frail ridge
#

So ∆abc has points a, b, and c in either cw or ccw

#

But it can't be a, c, b

#

Right?

silent plank
#

it can

#

well for a triangle it doesn't matter, it'll be in order no matter which way you arrange them

#

try as much as you can to screw it up

frail ridge
#

Now my second question

#

Do different names results to different triangles?

#

Given that both names share the same points

silent plank
#

wdym

frail ridge
#

Like I said before

silent plank
#

triangles ABC, ACB, BAC, BCA, CAB, CBA are all names for the same triangle

#

order doesn't matter

frail ridge
#

Okay then

silent plank
#

if you're referencing just a lone triangle

#

if you're doing stuff with similarity/congruence then
you'd order the names based on corresponding points

frail ridge
#

Finding the corresponding sides and angles

silent plank
#

you should always start with the original problem

frail ridge
#

My assignment is that given two triangles that are Cogurrent, enumerate all the corresponding sides and angles

silent plank
#

you can use whatever order you want for the first triangle
but for the name of the second triangle
the corresponding points will need to be in the same order

frail ridge
#

Ah I get it

#

So for ∆abc and ∆efg

#

Angle a and e are corresponding

#

Right?

silent plank
#

yes,

#

assuming they have been for some reason been represented with lowercase letters

frail ridge
silent plank
#

sides between the corresponding angles would be corresponding

lavish portal
#

Anyone does have idea 🌚

frail ridge
#

What does two capital letters together means?

#

No line above it, something like AB

nocturne remnant
#

The length of the line segment

frail ridge
#

How is it used?

nocturne remnant
#

Wdym how it is used

#

AB means the length of the line segment joining A and B. Like i just said

frail ridge
#

So I can say AB = BC if seg AB is equal in length as BC?

nocturne remnant
#

Yes

frail ridge
#

What is the difference between AB and AB with a line over it?

nocturne remnant
#

Some people use AB with a line over it to emphasise that they’re talking about the line(/line segment) itself rather than its length

#

Some people don’t put a line over it for any occasion

frail ridge
#

Okay then

#

Thanks

#

Sorry

#

One last question

#

What does <ABC mean?

nocturne remnant
#

The angle ABC

#

..have you not done any geometry at all????

frail ridge
nocturne remnant
#

Oh

frail ridge
nocturne remnant
#

You have a long way ahead of you then xd

frail ridge
nocturne remnant
#

The angle ABC specifically means “the angle formed by the arms AB and BC”

frail ridge
#

Is <AB also valid?

nocturne remnant
#

No

frail ridge
#

Good to know

nocturne remnant
#

Congruence

#

As they proved in the previous line

lavish portal
#

Oh I see 😁

vast trail
#

is this a soild geometry channel ?

dark sparrow
#

you can post solid geometry here

vast trail
#

what is the vol of a parallelpiped if he gave me the 3 points in 3d directions ?

dark sparrow
#

who's "he"...?

#

can you show the problem maybe

fossil lava
#

Guys I want to clarify something, if we have tan(nx) it's period is π/n right

native jay
#

Next time, google it

#

But yeah you're right

fossil lava
#

I don't know how to put them into words

native jay
#

type in "period of tan nx"

cobalt bone
#

help pls

grave pond
#

Note that cos(pi/6 - x) = sin(pi/3 + x). That gives a pretty nice set-up for using a sum-to-product formula.

lilac otter
grave pond
#

It just cos(a) = sin(pi/2 - a), and then simplify pi/2 - (pi/6- x) = pi/3 + x.

lilac otter
#

oh ok thank you very much

novel axle
upper karma
#

I need help with a test, I’m struggling

rough timber
#

how did they get ybar = 215

#

for the triangle

#

you would think it would be 45/3 = 15, no?

grave pond
#

Which triangle where?

upper karma
#

someone help

hollow turtle
#

i’m pretty sure this is really simple but i got it wrong:

a pyramid with a square base of a side length 8m has a height of 3m find the length of a sloping edge to once decimal place

silent plank
#

show your attemp

smoky jetty
# upper karma

you may find the value of the diagonal using Pythagorean theorem

#

where base^2 + height^2 = hypotenuse^2

#

since the diagonal cuts the rectangle into two congruent right triangles, then u can use the inverse of sin function (or the other trigo funcs) to find the angle (use calculator for convenience)

#

And refer to the theorems of parallel lines cut by a transversal so that you need not solve for the other right triangle's angle measures. Take note of the vertical angle theorem

astral bison
#

help ploz

smoky jetty
#

for the first part, I would say that "also a blop" is like a bigger set that the set of "something is a blip" is enclosed in. Though, I am not completely sure.

#

For the second part, u may do the Pythagorean theorem i.e sec(theta)= a/n

thin locust
#

is this correct?

thin locust
# astral bison

contrapositive since normal = contrapositive (in truth values)

smoky jetty
upper karma
#

after i subtract an area from another area, what is that red area called in english?

#

im a bit new to english math so i dont know those term

dark sparrow
#

dunno of a special word for that. is there a term for it in your language?

glad sphinx
#

remainder?

#

I don't know what to say

#

you can also say rectangular donut but I don't think that's a real word

valid comet
upper karma
#

imma die googling by myself to find that keyword

pliant pumice
#

Hello! My question is about triangle congruency. SSS - side/side/side rule is that if all 3 sides of 2 triangles are equal, they are congruent. The reason for this is showed on the picture. We can see that triangles AB1C and AB2C are absolutely same, but how do we prove that?

pallid vine
#

Knowing that AB1 and AB2 are radii of the left circle, CB1 and CB2 are radii of the right circle, each pair of those sides have the exact same length. From there, as you said, it will be SSS congruency as they also share the side AC

deft tiger
#

hie

#

can anyone help me

#

to prove : if a triangle has two angles equal to one another than the sides subtending the equal angles will also be equal to one another.

#

can anyone??

pliant pumice
pallid vine
river galleon
#

It feels like this should be easy. But i'm stumped

pliant pumice
bleak blade
timber cargo
# river galleon

Multiply the two side lengths by the sin of 114 and divide the whole thing by 2

#

Let me rephrase that

#

$absin(c)/2$

somber coyoteBOT
#

Daniel S.

timber cargo
#

@river galleon A and B being your side lengths, and sin(114 degrees)

river galleon
#

that was very helpful thank you

timber cargo
river galleon
#

not sarcasm

#

i do have a follow up question

#

what if you only have one side and two angles

#

for example 61 degrees 80 degrees and 17ft

#

to again find the area

timber cargo
#

Let me draw it out for you

timber cargo
river galleon
#

right. how did u acquire the height values

#

from 114

timber cargo
#

Are you asking, how to get 17 km

river galleon
#

from your example how you got 60 and 54

timber cargo
#

Drawing a perpendicular line that bisects the two side lengths

#

But notice that I added 30 degrees as the angle

river galleon
#

oh 30 60 90

timber cargo
#

Wait, I screwed up the triangle

river galleon
#

XD

timber cargo
#

But, do you get the idea/

river galleon
#

so when I find all the angles i can just use the same formula from before?

timber cargo
#

If the two side lengths are adjacent to the angle, then yes

river galleon
#

alright works for me yea.

#

thank you for your help

timber cargo
#

upper karma
#

A ship sails on a bearing of 156°T until it is 45 km south of its starting point. How far
east is it, correct to two decimal places?

#

help

grave pond
#

What does the T mean?

wind herald
#

can someone dm I have somethings I need help with

timber cargo
#

You know sending the problem here works too

#

In fact you'll get more people to help you

grave pond
#

Many helpers are motivated at least in part by the fact that they can be seen to be helpful and/or knowledgeable. If you want a closed DM conversation that motivation disappears.

floral shale
#

Shhh don't expose us

subtle palm
#

lol

neat plank
#

does anyone know how to solve or could point me in the right direction of finding the local min and max of 3/(4+2sinx-cosx) without differentiation?

silent plank
#

harmonic trig identity

upper karma
#

can someone explain to me wtf just happened

thin locust
#

given a convex quadrilateral ABCD where ABC + ADC = 180°, is the quadrilateral always cyclic

#

im not sure if
cyclic quadrilateral -> ABC+ADC=180°
or
cyclic quadrilateral <-> ABC+ADC=180°

upper karma
#

well think of it this way

#

can you imagine a quadrilateral where opposite angles add up to 180 and it isn't cyclic

thin locust
#

no

#

i tried drawing one

#

and im 99% that it isnt possible

#

but i may be wrong

upper karma
#

"The converse of this theorem is also true, which states that if opposite angles of a quadrilateral are supplementary, then the quadrilateral is cyclic."

#

I think this answers your question

thin locust
#

ah ok

#

ty

upper karma
#

supplementary angles are angles adding up to 180

thin locust
#

yes thank you

upper karma
thin locust
#

could this be proven by dividing the quadrilateral into 4 right triangles

#

and then wait

#

let me try it

#

nvm

#

but thank you

latent compass
#

I can’t find the answer anywhere on google so 😭

thin locust
#

1.since ABC = ADC = 90, ABC+ADC=180 -> cyclic

2.since ABC=90, then AOC has to be 180 -> A, O, C are colinear -> diameter

#

this is correct right?

blissful spire
#

I just started learning about tangents and stuff and I’m confused how to solve for x here

floral shale
#

Remember that tangent is opposite/adjacent

blissful spire
#

Ok

#

Wait what is opposite/adjacent?

#

That would mean it would be tan(49)=14/x?

#

If I did it correctly I got x=16.1056

#

How do I solve for an angle using tangents when I have all the sides and a 90 degree angle alr?

#

Like this

upper karma
#

help

trim lion
#

bru

#

rhombus

scarlet shell
#

Could anyone dm me a good trigonometry book recommendations? 😄

timber cargo
#

Then you base times height your way to victory

upper karma
timber cargo
# upper karma

Use your knowledge of angles and trig functions to solve this problem

upper karma
upper karma
#

then just add all of it up

sage bison
viscid shoal
#

Hi, can I get a help or tips about these problems?

What is the area of quadrilateral ABCD given 2 sides and radius of inscribed circle? AD= 5cm, BC = 4cm, radius of circle is 2 cm

And how to find the length of a radius of circumscribed circle around a regular hexagon, if I know the length of the radius of inscribed in it circle (it is 6√3 cm)?

smoky jetty
# upper karma

also has something to do with special triangle 45-45-90 caSE

silent plank
glad sphinx
chilly zinc
# blissful spire Like this

Set up your equation as normal with SOHCAHTOA, but this time, theta is your unknown variable. You'll have to solve for theta using an inverse tangent

crisp valley
timber cargo
#

I.e. tan, sin, cos

crisp valley
#

Can you just give answers

#

Nevermind i threw the paper away

timber cargo
crisp valley
#

@timber cargo Bro be fr

smoky jetty
#

we're here to guide you on getting it.

golden nymph
#

Could someone point out my error here? The answer should be 0 if you use the 1+tan^2(5) identity. But shouldn't this work too? I'm sure it's a stupid mistake, but I'm not seeing it.

exotic yarrow
golden nymph
#

Why?

exotic yarrow
prime musk
#

Cos square theta plus sine square theta is one

somber coyoteBOT
#

Civil Service Pigeon

golden nymph
#

🤣 I knew it was something stupid. Thank you!

deep vapor
#

good afternoon , i don't know ,what i did wrong

leaden seal
arctic breach
#

Determine all values of k for which the points A=(1,2), B=(11,12), and C=(k,6) form the vertices of a right-angled triangle.
I tried this using the pythagorean theorem by calculating AB^2, AC^2, and BC^2 and using the Pythagorean theorem but i'm not getting the right answer

nocturne remnant
arctic breach
#

AB^2 = (11-1)^2 + (12-2)^2 = 200
AC^2 = (k-1)^2 + (6-2)^2 = k^2-2k+17
BC^2 = (k-11)^2 + (6-12)^2 = k^2 - 22k + 157

leaden seal
#

Isn’t it all the points on a circle

arctic breach
#

AB^2 + AC^2 = BC^2
simplifying this you get k = -3

#

if you sub in the values

#

the answer is supposed to be 1 and 11 i believe

nocturne remnant
#

so you assumed A is the right angle

#

I think that's the problem

arctic breach
#

i did the other ones too

#

and none of them were 1 or 11

nocturne remnant
#

hmm

#

probably some algebra mistake then

nocturne remnant
#

it's supposed to be 2 i think

upper karma
#

I NEED HELPPP

leaden seal
#

This is every point for a right triangle using those 2 points

#

I think

nocturne remnant
leaden seal
#

Why are there 2 answers?

#

The y value is equal to 6

upper karma
#

Ion know y this is wrong... what's my mistake?

arctic breach
nocturne remnant
#

hmm whatttttttt

#

i think the answers are k = 1, 3, 9, 11

arctic breach
#

how do you get that?

nocturne remnant
#

for k = 3 and 9 <ACB is 90 deg

#

for k = 1 <CAB is 90 deg

#

for k = 11 <ABC is 90 deg

arctic breach
#

but how did you find those numbers?

nocturne remnant
#

for k = 1 and 11 should be obvious

#

the other ones i used desmos

arctic breach
nocturne remnant
#

well line AB is horizontal right

#

so if k = 1 then AC is vertical and CAB = 90

arctic breach
#

isnt AB on an angle?

nocturne remnant
#

?

arctic breach
#

if its going from (1,2) to (11,12)

nocturne remnant
#

oh

#

your problem then

arctic breach
#

oh yes sorry i wrote the wrong number

nocturne remnant
arctic breach
#

i meant 11,12

nocturne remnant
#

hmm

#

in that case it's even weirder than k = 1 and 11 is the given answer

maiden kelp
#

?

arctic breach
#

i screwed up the numbers

#

Determine all values of k for which the points A=(1,2), B=(11,12), and C=(k,6) form the vertices of a right-angled triangle.

#

the answer is 1 and 13

nocturne remnant
#

huh i got -1, 13 and others

floral shale
# upper karma Ion know y this is wrong... what's my mistake?

Knowing that $C = 2\pi r \implies r = \frac C{2\pi}$, we can say that:

$$\begin{align*}
A &= \pi r^2 \
&= \pi\parens{\frac C{2\pi}}^2 \
&= \frac{C^2}{4\pi}
\end{align*}$$

You can plug in $C$ directly. It's probably an intermediate rounding error that caused you to goof up because your work is fine.

somber coyoteBOT
#

Umbraleviathan
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

floral shale
#

Although it only wants points on the circle where y = 6

#

Which has two answers

#

Either you use projection or pythag

#

Although your circle uses (11,2) instead of (11,12)

deft helm
#

Please help. (This is probably a easy geometry question, but I don't know how to do it)

timber cargo
#

24 is proportional to 8 as 10 is to x

#

so

#

24-8
10-x

#

solve for x by cross multiplying

#

or you can just do this intuitively

#

and see that it’s 10/3

#

^ This should help you with analyzing future problems

deft helm
#

Oh sorry I was afk

#

And thanks for the answer

timber cargo
deft helm
#

I think that if the shape of both of the triangles is similar, it is proportional.

smoky jetty
#

the bigger one was essentially just scaled up to a factor of 3

scarlet shell
vernal parrot
#

can someone help me with my problem (help -12)

sick hemlock
#

You probably shouldn't have rounded the value of r at the start

#

Just kept it as it is, square it and multiply with pie

timber cargo
#

You rounded your r, don't do that

dusk marten
#

do vectors belong here or somehwere else

static magnet
#

can someone please explain this to me

#

because 36.8*2

#

and 180- the sum = 106

#

which is wrong

#

and hwo they got the equation at the bottom

#

complete ss

#

or how do they prove tan^2 x = 0.5

#

I dont' understand that part

viral merlin
#

why does a conic section always touch the cone in one point?

#

<@&268886789983436800>

floral shale
viral merlin
floral shale
#

Ah yes

viral merlin
#

very weird porn

floral shale
#

My favorite math topic

#

Porn

#

(Parabolic horns)

cold chasm
#

what are tangent circles

valid comet
#

circles that touch each other at exactly one point

maiden kelp
#

wht

timber cargo
#

Solve for x

#

y+(3x+19) are supplementary

#

they add up to 180 degrees

#

If you know what x is, you’ll know what y is

maiden kelp
#

so 5?

#

then for y we plug the x into y+(3x+19)?

#

x=5 y=24?

grave pond
#

If x is 5, what is then 3x+19?

maiden kelp
#

oop i ment 34

#

lol

#

anyways thx for your help

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lol it was wrong

grave pond
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Yes, but does 34 + 24 make 180?

maiden kelp
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no

tender rain
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Is anyone good with factors ?

grave pond
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So x=5, y=24 is not a solution.

cunning acorn
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can someone help me with this please

cunning pumice
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could someone teach me how to identify the side lengths

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i'm not sure why it's so difficult for me

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i feel like it should be easy

gilded lion
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Find RQ and Triangle of PRQ

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me and my whole class has trouble with this 😂

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ifa nyone wanna help

atomic moat
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should PR is = 3.2^1/2

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?

foggy parcel
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u shouyld extand the line PQ

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and create a perpeniducular from R to that line

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then u can use the cosine

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to identity the whole adjacent line

smoky jetty
smoky jetty
foggy parcel
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like this

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extand the PQ

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and draw a perpendicualr

gilded lion
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tysm

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god bless

foggy parcel
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my plesesure

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have u got what u have to do

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?

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U can use cosine to get the value of PQ'

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then u can get QQ' and same way u can get the valuye of RQ' using sine

floral storm
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hey,,

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what are your POVs about existence of perfect cuboid

smoky jetty
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or im confused, lol

foggy parcel
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cos 15deggres = PQ'/PR

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in the triangle PRQ'

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Pr = 10

smoky jetty
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oh wait

foggy parcel
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SO from here u can get the value of PQ'

smoky jetty
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I essentially just got the value of PQ'

foggy parcel
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Okay good

smoky jetty
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since it's a right triangle, i just did 10cos45deg.. is this correct?

foggy parcel
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ah u should just use cos15

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wait

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is the angle 45 or 15

smoky jetty
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for triangle PRQ'

smoky jetty
foggy parcel
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Oh lol

gilded lion
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45*

foggy parcel
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Oh then u can just use cos 45

gilded lion