#geometry-and-trigonometry

1 messages · Page 46 of 1

rugged shuttle
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Wait @dark sparrow

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How would I prove 21

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If tan (pi/2) is undefined??

dark sparrow
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tan(pi/2) is indeed undefined

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what route did you try to go?

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@rugged shuttle

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pings me
doesnt respond

rugged shuttle
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I just tried to use tangent subtraction formula

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But quickly found out that it doesn’t work .-.

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Also sorry

dark sparrow
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the instruction does say to use the angle sum/diff formulas, but it does not specifically say to use the ones for tan.

rugged shuttle
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Omg ur the best

faint comet
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Does anyone know where I can find some trig proof questions and questions on general soloution

spice hornet
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I was practice with the regular way and the inverted way. Finally got it.

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I don't think the recipricals ones aren't too important

faint comet
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Yo guys

spice hornet
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Like I just have to flip a fraction. But is that an important question that I need to be like "oh I need to flip"? Besides a very obvious way of asking to

faint comet
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Does this work for general soloution (ignore handwriting im high asf)

rugged shuttle
cyan latch
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Does trigonometry equations use radians or degrees more?

obsidian harness
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You only use degrees until you know how to use radians

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Cause sin(x) in degrees has some bad properties for if you are using trig functions in calculus

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E.g sin(x)/x only approaches 1 as x approaches 0 in radians

cyan latch
obsidian harness
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And the derivative of sin(x) is cos(x) only in radians (in degrees you would need to multiply by pi/180)

cyan latch
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Cause i can simply put degrees into a calculator

obsidian harness
obsidian harness
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pi radians = 180 degrees

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remember the conversion and you're good

cyan latch
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I guess so

obsidian harness
obsidian harness
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Okok

cyan latch
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I use a 25 euro scientific calculator

obsidian harness
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cool

cyan latch
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But its genuine garbage

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Ill probably buy a new one

cyan latch
dark sparrow
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radians are not something mystical

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they are just another unit of angle

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any angle can be expressed either in degrees or in radians, and it is a matter of convenience and contextual appropriateness which unit is to be used.

solid needle
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100-4% is actually correct though

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% = 1/100

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100-4% = 100 - 4/100 = 100 - 0.04 = 99.96

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i see no problems with that one

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students should properly understand the arithmetic operations when handling percentages

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you should do 100(1-4%) or 100(96%)

cyan latch
cyan latch
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but i do like your style

cyan latch
snow plinth
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Define a parallel rectangle P in R^n to be an n-fold Cartesian product of compact intervals, so its sides are parallel to the coordinate axes. Let an oblique rectangle O be a rectangle whose sides are not parallel to the coordinate axes; it is obtained as the image under an orthogonal transformation T of a parallel rectangle, so T(P)=O. An almost disjoint collection of sets means that the sets intersect each other at most along their boundary. v(.) is the volume of a rectangle, i.e. the product of the length of its sides (where length of say [a,b] is simply b-a). Note, that since an orthogonal transformation preserves lengths and angles, we have v(P)=v(O).

Consider then the following lemma in my lecture notes:

somber coyoteBOT
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Philip

snow plinth
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How hard is it to prove this lemma? Do you know a proof or a reference where this is proved? I'm grateful for anything! Prior to this, the author has proved some results about parallel rectangles which may be useful in proving the above lemma. If you want to know more, let me know and I'll post some more results the author has already proved.

fickle cosmos
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I feel like I did this right .....

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but it seems a bit off**...**

rugged shuttle
faint comet
upper karma
upper karma
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There’s no need to use pi in this case

faint comet
upper karma
upper karma
faint comet
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Ahh ok

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And if it went through postive 3 then it would be postive ?

upper karma
twin python
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Can someone help me find x

dark sparrow
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@twin python do you still need help with this? if yes, share all progress you've made so far.

twin python
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Yes

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I can't figure out tbh

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I jolted the remaining angles but I still can't figure out

dark sparrow
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jolted?

twin python
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Noted

dark sparrow
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ok

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so let me ask you first a conceptual/vocabulary question

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do you know the word that describes the placement of these angles relative to the polygon?

twin python
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Exterior angle

dark sparrow
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right.

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now tell me: what do you know about the exterior angles of a polygon?

twin python
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M not sure

dark sparrow
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what do they all add up to?

twin python
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360

dark sparrow
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and you claimed not to know that...

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but ok, now you've stated it.

twin python
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Oh shoot I forgot sry

dark sparrow
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the exterior angles add up to 360°.

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as you yourself said.

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do you see how to do your problem now?

twin python
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Thank u very much

upper karma
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Hello

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Does anyone know how to simplify this

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I tried using the double angle cosine formula but it didn't help at all

dark sparrow
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what's the goal?

upper karma
dark sparrow
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why not look at the numerator

light dock
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oh let's go this is my favorite trig identity

upper karma
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I used photomath

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It didnt solve it

light dock
dark sparrow
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that's your reason for not following my suggestion?

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or i guess that wasn't meant as an answer to my question

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so i'm going to reiterate:

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look at the numerator

upper karma
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Ok

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Oh i got it

light dock
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epic

upper karma
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It is 1/2 tg 6a

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Right?

dark sparrow
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the whole thing simplifies to that, yes.

upper karma
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Ok, thanks

light dock
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i miss when they would put smiley faces with sunglasses when i got things right

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unrelated to the problem itself

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it's a good feeling

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to me

upper karma
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By the way

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What do you mean by saying "trig identites"?

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Does it mean trig formulas or functions?

light dock
dark sparrow
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shit like sin^2(x) + cos^2(x) = 1

upper karma
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Got it

light dock
# upper karma Got it

for example, when you have an equation, say, sin(x) = 1, you can ask the question, "is this an identity?" and the answer would be no, since sin(x) is not always 1

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but you can ask something like Ann said, like "is sin^2(x) + cos^2(x) = 1 an identity?" and then the answer would be yes

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becuase we know that this is true no matter what x is

upper karma
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Thanks. I understand it

uncut totem
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Hello everyone. The condition of the task is to find the two sides of the isosceles trapezoid with the information given in the drawing. The correct answer should be 13√10, but somehow I got 13√8. I struggle to find my mistake

dark sparrow
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1521 + 169 = ?

uncut totem
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lol

dark sparrow
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без да искаш си извадил числата вместо да събереш

uncut totem
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не забелязах

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благодаря

lilac narwhal
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e^ipi = exp(ipi)

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why do we not use the exp() form?

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It seems simpler

upper karma
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e^ix can be abbreviated to cis(x) anyways

lilac narwhal
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Right

upper karma
lilac narwhal
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I kinda thought it was due to the cosx and isinx

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Precalculas?

upper karma
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Maybe

weary haven
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Does anyone here study spherical trigonometry?

upper karma
weary haven
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Nice

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Have you found it useful

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Or is the subject obsolete in terms of applications?

north kindle
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Applications are for nerrrrrrds

weary haven
dark sparrow
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i mean, navigation is a thing

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would imagine that spherical trig has that as its biggest application

upper karma
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Celestial sphere calculations, stars transit time, celestial coordinates system conversion

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As well as calculating great circle distances

weary haven
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I just studied spherical trig for fun, not because it will be useful for anything

upper karma
grim notch
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i came across a super hard non euclidean geometry problem

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in my hw

tribal sequoia
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dang what's the problem

faint comet
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How long did it take you guys to get good at trig proofs ?

tribal sequoia
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around a week or so.

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wdym by good

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basic trig proofs or complicated onnes

maiden brook
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pretty nice thing i saw: every convex quadrilateral can be disected into seven convex kites like this, for example

mortal crow
tall coral
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Assume $a^2+b^2=c^2
\newline c^2=b^2+2b(c-b)+(c-b)^2
\newline a^2 = 2b(c-b)+(c-b)^2
\newline a^2=2bc-2b^2+c^2-2bc+b^2
\newline a^2=-b^2+c^2
\newline a^2+b^2=c^2$

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a little pythagoras theorem proof I made, not sure how to prove a^2 is equal to that expression though, of if I even need to.

somber coyoteBOT
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KirbysGames

wanton edge
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Did you just assume that a² + b² = c² to prove that a² + b² = c²? That looks like circular argument

tall coral
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i have no clue how to prove a^2 though

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(I'm also just not good at geomertry proofs ughh)

tall coral
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or I guess it'd be better to say
\newline Let b and c be sides of a triangle such that c is greater than b
\newline $\exists a, b^2+a^2=c^2$

somber coyoteBOT
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KirbysGames

tall coral
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yeah, that's much nicer

faint comet
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How do i Write a general solution for a trig equation

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Like most of the time should I join the join angles together in 1 line or leave it seperate with angle +2piN

dark sparrow
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like if you write {π/4 + 2πn, 3π/4 + 2πn | n ∈ Z} that's perfectly ok

faint comet
dark sparrow
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gonna need to hear the exact formulation of that requirement.

velvet bone
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from https://en.wikipedia.org/wiki/Delaunay_refinement

Chew's second algorithm
...
At each step, the circumcenter of a poor-quality triangle is inserted into the triangulation with one exception: If the circumcenter lies on the opposite side of an input segment as the poor quality triangle, the midpoint of the segment is inserted.

What do they mean by "input segment" here?

obsidian harness
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The circumcentre can lie outside the triangle

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So it would be lying on the opposite side of say side YZ

velvet bone
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so, that is what they meant? that the point is outside triangle?

obsidian harness
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Hopefully

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I think you'd have to read the papers linked in the references to understand what they mean

velvet bone
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this is what I thought initially too but that would be a really weird to phrase it

obsidian harness
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IDK

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I hate when technical writing doesn't make any sense

velvet bone
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my other assumption was that they talk about points that lie outside of constrained geometry, that would make more sense

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not just triangle one single, but global boundary instead

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well, still, what's input segment?

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maybe they mean the longest edge of a triangle?

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because it lies against worst angle in the triangle?

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so, if the circumcenter is outside triangle, we divide this longest edge in half instead?

obsidian harness
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Yeah I guessed that's what they mean

velvet bone
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is this algorithm good if I target edge size instead of angle?

velvet bone
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(well, and for right triangles both are the same location)

obsidian harness
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Yeah why don't they communicate clearer...

hallow flare
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Is this right

clear anvil
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how would i find the diagonal?

fallow sonnet
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how do i do this i have no idea

spark tree
# clear anvil

Look form a right triangle for the 6 and 3 and get the hypotenuse same for the three and 4 . Then draw the other diagonal for the square. Then get the angle for the 3,4,5 triangle opp 4 adj 3 so tan4/3 + 90 then use the cosine rule to get the diagonal

spark tree
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Both diagonals are equal anyways

clear anvil
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but this is a geometry problem lol

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ideally you don't need trig

spark tree
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Huh?

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You can’t solve it otherwise

clear anvil
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you can

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with pythag

wanton edge
clear anvil
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what is it?

spark tree
clear anvil
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You literally can

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Smh

spark tree
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Ok so how?

wanton edge
spark tree
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Ok? Now what?

wanton edge
clear anvil
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hard to draw with a sketchpad but yeah you didn't need trig at all for this

spark tree
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Oh wow good job dude

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Well i could have gotten it if i drew but am not home lmao sorry for doubting you 💀

crystal sand
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i can just ask for help here righy

wanton edge
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just post a question with full context

trail tendon
crystal sand
ember grove
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At first when i saw addition formulas and proofs i was like " why don't you just add the output of sines and that's it" but then I forgot that we are talking about functions not just simple direct numbers. I don't understand completely why but i guess due to the fact that a function follow a certain system of correlation like in the case of trig functions. They are not just direct values but fractions. What do you think?

trail tendon
crystal sand
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i think for the value it goes with would 5pi/4

trail tendon
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for what value?

crystal sand
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-1

trail tendon
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um

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i mean its true but are there any other values?

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wait its not true actually

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💀 mb

trail tendon
crystal sand
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you would need to find -1 on the unit circle

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like the one that matches up with it

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and then you would need to find theta

trail tendon
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not exactly

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i'm going to call the value x ok?

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like x = theta/2 + pi/4

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right

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so like tan(x) = -1

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are you following or nah xD

crystal sand
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yea

trail tendon
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ok

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tanx = sinx/cosx right?

crystal sand
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ok

trail tendon
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im just gonna get a picture of the unit circle

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you're looking for a point where sinx/cosx = -1

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cos is the x value

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sin is the y value

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of each point

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right?

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if this doesnt make sense at any time lmk lol

crystal sand
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yea this is hard part for me

trail tendon
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ok

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look at 60 degrees

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60 degrees = pi/3

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the (x,y) coordinates here are (1/2 , (sqrt(3) )/2)

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the 60 degrees or pi/3 are the inputs of a trig function

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like sin(60 degrees)

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or sin(pi/3)

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sin(60 degrees) means the y value at the "60 degree" point

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i'm not explaining this well 😭

crystal sand
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uh

trail tendon
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do you see the (x,y) points?

crystal sand
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yea

trail tendon
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ok

crystal sand
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but if u do sinx/cosx

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itll give me sqrt 3

trail tendon
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thats if x is 60 degrees

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so you kinda want to find where the degree gives a point (x,y) such that y/x = -1

crystal sand
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i know that much

trail tendon
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ok

crystal sand
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is it just to a point of memorization?

trail tendon
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kind of

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but also

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you're dividing two numbers to equal -1

crystal sand
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yea but am i just supposed to guess to figure out which two point equal to -1

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like the angle

trail tendon
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um yes...

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but it isn't too hard

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because you know if you divide two numbers and you get 1

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they have to be the same number

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so what happens if you divide two numbers and u get -1

crystal sand
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so sqrt2/2. sqrt2/2?

trail tendon
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but we're looking for tan(x) = -1

crystal sand
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so one of them is negative

trail tendon
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yes

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either one, but not both

crystal sand
#

both would be positve?

trail tendon
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like the x can be negative, or the y value can be negative, but the x and y cannot both be negative, or the x and y cannot both be positive

crystal sand
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3pi/4 and 7pi/4

trail tendon
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yeah

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and keep in mind you could keep adding pi, but they limited you to only be from 0 to 2pi

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like you could get 11pi/4 and its the same as 3pi/4

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but its out of the domain

crystal sand
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ye

trail tendon
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so anyway

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x = theta/2 + pi/4
x = 3pi/4 and 7pi/4

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do u know how to continue

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from there

crystal sand
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it has something to do with 3pi/4+2pik

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i would move the pi/4 over

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amd then mult by *2 to get the theta alone

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or x

trail tendon
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you'd set x = 3pi/4 and solve for one solution of theta, then set x = 7pi/4 to solve for the other soltuion of theta

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yeah

crystal sand
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would i multiply everything by *2?

trail tendon
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sure that would work

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to get theta alone

crystal sand
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i got pi+4pik

hexed rock
dark sparrow
#

!redir

lime crownBOT
#

This channel is only for on-topic discussion. Please take casual conversation to #discussion or #chill.

gusty crane
#

how do i find the surface area for problem 13

maiden brook
#

how do u do this 😭 i got that BC is 7 and drew a diagram but then what?

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there are also similar triangles but u need more

dark sparrow
maiden brook
dark sparrow
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aight lemme see...

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triangles AZY and ABC are similar

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could do something with that i think

maiden brook
#

u need more

dark sparrow
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let β := angle B (which is equal to angle AYZ of course)

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then angle AZY = 120° - β

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and angle BZX = β

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so it would appear triangle BXZ turns out isosceles

maiden brook
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yeah

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and then what?

dark sparrow
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XYC is isosceles as well

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with some more angle chasing

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mark off in both triangles which sides are equal

fervent halo
#

can someone help me find l6?

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i can pay

maiden brook
dark sparrow
#

so it would appear

dark sparrow
fervent halo
#

shhh

dark sparrow
#

<@&268886789983436800> we got a payment solicitor

obtuse field
#

@fervent halo please stick to asking your question in one place in the server, and don't offer to pay for help

fervent halo
#

did i ask anywhere else?

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i thought it was fitting to ask here since its a trigonometry chat

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sorry

obtuse field
#

please just ask in one place

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it is on-topic, but we'd rather not have the same question posted in a bunch of different places in the server

fervent halo
#

mb

fervent halo
#

How do I solve the Riemann hypothesis?

north kindle
#

Step one: assume the reimann hypothesis is true
Step two: if the reimann hypothesis is false, this contradicts the assumption that the reimann hypothesis is true
Therefore, the reimann hypothesis must be true
Q.E.D. /s

raven dove
#

is this riight wat i did?

maiden brook
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what is that last step

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the reciprocal isn’t the same?

raven dove
#

ye yu right

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i figured it out just now

raven dove
fathom stone
#

I need to find the radius of the circle with an equilateral triangle inscribed in it but for the sides I have 2 lengths that can be the side length of the triangle since everything I did led to ⊾BAC=⊾BCD=90

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this is the question

maiden brook
final vale
#

System: tg(x)=-1 and cosx<0. Help please

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I predict answer is x=-Pi/4+Pn, where n€Z

sick vessel
#

est ce que vous pouvez parler francais

foggy tartan
#

x=(3pi/4)+2kpi k in Z

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ouii o

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oui je parle fr

sick vessel
#

tu pe mexpliquer le tehoreme de tales

foggy tartan
#

celle de triangle

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oui

sick vessel
#

oui stp

foggy tartan
#

d acc . mais ou tu veux je t ecris

sick vessel
#

au pire laisse tomber merci quand meme

faint comet
#

What’s argument angle ? Is it angle the angle that is the closest to the postive x-axis from your angle

scenic merlin
#

to find the negatives, do we ALWAYS go clockwise
im so confuse rn when doing other practice questions

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all this arrow directions got me confused back when hs physics had the hand signs

obsidian harness
#

Angles are measured anticlockwise from the positive x-axis, by definition

obsidian harness
#

The right-hand rule?

scenic merlin
obsidian harness
scenic merlin
foggy lintel
#

I need more difficult problems in the field of analytic geometry with solutions

jaunty sail
#

ABCA1B1C1 is a regular triangular prism, the sides of the base and the side edge have a height of 6. A secant plane is drawn through the base of the edges AC and BB1 and the vertex A1 of the prism. Find the cross-sectional area of ​​the prism of this plane.

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How to solve it?

tidal tulip
#

Tbf mate I don’t know

trail tendon
#

i can't visualize it 💀

sudden shell
#

I forgot how to find EA and FB Can someone help me out

lime dune
#

not enough information, show us the entire problem statement

halcyon sierra
halcyon sierra
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AE=20

sudden shell
halcyon sierra
#

Since E and F are midpoints, AE =BF=20

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all sides are equal

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40/2 you get the midpoint

sudden shell
#

40/2=EF

halcyon sierra
#

yea

sudden shell
#

So how you know EA if we have nothing on CA

halcyon sierra
#

the sides are all equal

sudden shell
#

Oh I’m so stupid

sudden shell
halcyon sierra
#

no problem

strong vault
#

Heyy does anyone know how the perimeter of e is 46 cm

dark sparrow
#

do you think the perimeter should be something else?

pseudo jackal
jaunty sail
dark sparrow
#

then make a diagram lol

jaunty sail
#

lol

dense garnet
#

Nvm that wasn’t trig

crisp yarrow
#

can someone explain how the answer is C?
I worked it out and I got -cos(x)-2 in contrast to the answer 2-cos(x)

rich scroll
#

Im confused in number 18, letters a and b seems promising to me.

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Number 17 as well

lime dune
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a and b are both incorrect for 18

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you cannot apply "isosceles triangle theorem" when the equal angles are in two different triangles

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||c|| is the answer to 18, to see this ||consider the two angle equalities you have and the fact that the angles of any triangle sum to 180 degrees||

scenic merlin
#

There’s 4 answers in this question
What am I supposed to do for the remaining 3? Or did I do something wrong? This is as far as I can remember what to do when referencing to my lecture video in its examples.

dark sparrow
scenic merlin
dark sparrow
#

hm

crisp yarrow
#

what about -2pi/3?

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thats one as well

dark sparrow
#

i would say that you would do well to first get the general solution.

crisp yarrow
dark sparrow
#

sin(3y/2) = -sqrt(3)/2

y = -π/3 + 2πk, y = -2π/3 + 2πk, for k in Z

dark sparrow
#

it will help you not fuck up which solutions are included and which are not

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so it's anything but

crisp yarrow
#

I would just get the first two values of -root3/2

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which is -pi/3 -2pi/3

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then minus 2 pi from both

dark sparrow
crisp yarrow
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then boom u have ur 4 solutions

dark sparrow
#

i mean sure you can also step up/down by 2pi

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until you are out of the interval

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amounts to the same shit

dark sparrow
#

those should actually be 3y/2 not y

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i forgor to include the 3/2 factor

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so the general solutions for y would be
y = -pi + 4πk/3, y = -2pi + 4πk/3

scenic merlin
crisp yarrow
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No need for general solution lol

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@scenic merlin

torpid tinsel
#

helloo

river falcon
#

A right angled triangle has one 90° angle

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It obeys the pythagoras theorem and its area is the easiest to find

torpid tinsel
#

does it also obey trig ratios?

river falcon
#

Equal to the (area of a rectangle with the same side lengths)÷2

river falcon
torpid tinsel
#

ohhhhh, it's starting to make more sense now

torpid tinsel
river falcon
#

A rectangle cut in half diagonally is a right angled triangle

torpid tinsel
#

ur so right wth

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HAHA sounds simple, i'm just super slow 😭

river falcon
#

That's about it idk what else to tell you ask any doubts

torpid tinsel
#

all i needed to know for now really

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thank you for your help!

river falcon
#

You're welcome

twilit surge
#

can someone help me find the area of a kite

hexed crater
#

depends on what youve been given tho, send a photo of the question

hexed crater
#

okay so

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look at the top triangle

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its base is the long horizontal line, whihc is 40+3 = 43ft.

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height of the top triangle is 8 ft.

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area of a triangle = base x height x 0.5

#

so area of top triangle = 0.5 x 43 x 8 = 172 ft^2

#

bottom triangle is also 172 ft^2, same procedure

#

so total is 172+172 = 344 ft^2

twilit surge
#

imma see if it's right rq

hexed crater
#

yeah check

twilit surge
#

Yeah it was right

#

thank you 🙏

hexed crater
#

there u go then, np

#

theres also a general formula for area of a kite

#

but u can just do this, more intuitive

dark sparrow
lime crownBOT
dark sparrow
#

you ended up doing the entire thing for him

hexed crater
#

ah okay sorry

swift light
#

huh???

teal fjord
rugged shuttle
#

What’s the product to sum formulas for (cos a)(sin b) and (sin a)(cos b)? Or what’s the difference?

trail tendon
#

sin(a+b) = sin(a)cos(b) + cos(a)sin(b)
sin(a-b) = sin(a)cos(b) - cos(a)sin(b)

rugged shuttle
#

Oh nvm I found it

trail tendon
#

oh sorry i didnt see product to sum 💀

trail tendon
rugged shuttle
#

Lol it’s fine

#

,help

somber coyoteBOT
#

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

rugged shuttle
#

,tex sin $$8x$$

somber coyoteBOT
#

Cyberr

rugged shuttle
#

,tex sin 8x

somber coyoteBOT
#

Cyberr

rugged shuttle
#

,tex sin 8x = 2(sin 4x)(cos 4x)

somber coyoteBOT
#

Cyberr

rugged shuttle
#

Yo I did it

#

@empty yew wanna try this problem (verify identity)

jagged wyvern
#

Could someone tell me if i'm doing this right? Im not really good at word problems, but i tried to visualize it out

I assumed kite was 300m away, so it's HYP
And 53 degrees is greater than the other angle so it's going to the longer side
Sin(53) = x/300
Sin(53)(300) = x
x = approx 239.6

And since my hand is 4 feet above the ground, I add 4 to 239.6?

So 243.6? Someone pls confirm

jagged wyvern
#

<@&286206848099549185> 15 minutes

gentle haven
#

I believe you are right

#

Are you able to check your answer?

#

I'm assuming you are using bim

jagged wyvern
jagged wyvern
trail tendon
#

they should have specified the distance between what and what, but i think its safe to assume they meant the distance from your hand to the kite

#

and if that is the case, then yes it is the hypotenuse of the right triangle

#

otherwise there would be no trigonometry 🤣

#

that's not why i came to that conclusion, but it is funny lol

jagged wyvern
#

my bad

#

it's just the word problems that mess me up

trail tendon
#

i agree

jagged wyvern
#

like which values are the HYP, and the height, because you have to visualize the stuff

trail tendon
#

that word problems mess you up

#

XD jk

#

word problems are hard for me too lol

jagged wyvern
#

Ye..

jagged wyvern
#

Ty for the help

rugged shuttle
#

,tex tan(x/2) + csc x = (2-cos x)/sin x

somber coyoteBOT
#

Cyberr

rugged shuttle
#

,tex tan 3x = (3tan x-tan^3x)/(1-3tan^2x)

somber coyoteBOT
#

Cyberr

tan 3x = (3tan x-tan^3x)/(1-3tan^2x)
```Compilation error:```! Missing $ inserted.
<inserted text> 
                $
l.49 tan 3x = (3tan x-tan^
                          3x)/(1-3tan^2x)
I've inserted a begin-math/end-math symbol since I think
you left one out. Proceed, with fingers crossed.

LaTeX Font Info:    Trying to load font information for OT1+lmr on input line 4
9.
(/usr/local/texlive/2023/texmf-dist/tex/latex/lm/ot1lmr.fd```
rugged shuttle
#

,tex $$tan \frac {x}{2} + csc x = \frac {2-cos x}{sin x}$$

somber coyoteBOT
#

Cyberr

rugged shuttle
#

,tex $$tan 3x = \frac {3tanx-tan^{3}}{1-3tan^{2}x}$$

somber coyoteBOT
#

Cyberr

rugged shuttle
#

Can someone help me prove these 2 identities?

#

Here is my work

dark sparrow
#

any reason why you are writing so small?

dark sparrow
dark sparrow
somber coyoteBOT
dark sparrow
#

oh wait, it looks like you tried to square both sides but then fell victim to freshman's dream on the left.

#

also in the tan(3x) one you didn't seem to fuck up (yet), all that remains on the LHS is to multiply outer num and denom by (1-tan^2(x)) as per standard nested fraction clearing procedure

rugged shuttle
#

Yo I got 87

#

It became clear when I put everything over 1-tan^2 x

#

I write small cuz I try to fit everything in 1 page

#

I’m new to tex so…

#

Hehe

#

Bruh no…

#

@dark sparrow I got $\frac {{1-\cos x}^{2}}{1-\cos^{2} x} = \frac {2-\cos x}^{2}{1-\cos^{2} x}

#

Bruh

#

$\frac {{1-\cos x}^{2}}{1-\cos^{2} x} = \frac {2-\cos x}^{2}{1-\cos^{2} x}$

somber coyoteBOT
#

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

rugged shuttle
#

BRUHHHHH

dark sparrow
#

you would do well to write a little bigger so that both you and whoever's reading your work don't have to use a microscope.

dark sparrow
#

you cannot go from
tan(x/2) + 1/sin(x) = (2 - cos(x))/sin(x)
to
tan^2(x/2) + 1/sin^2(x) = [(2-cos(x))/sin(x)]^2

#

do you understand why? yes or no.

rugged shuttle
#

I forgot

dark sparrow
#

there's this lovely identity

#

$\tan(x/2) = \frac{1 - \cos(x)}{\sin(x)} = \frac{\sin(x)}{1 + \cos(x)}$

somber coyoteBOT
dark sparrow
#

the first half of which kills your problem

#

without any need for squaring

rugged shuttle
#

#

I have never seen this identity before in my life

#

Ok let me try the problem again

#

BRO I DID IN LITERALLY 3 steps

#

@dark sparrow how was this identity derived

#

Anyways I gtg so thx !

spice hornet
#

How does one get a root 3 /3

dark sparrow
#

are you asking how tan(30°) = sqrt(3)/3?

spice hornet
#

Yes

dark sparrow
spice hornet
spice hornet
#

Where I was looking he was teaching how to find missing sides for various triangles

dark sparrow
#

ochem tutor assumed that you know this value and used it to find some side lengths in his problem

spice hornet
# dark sparrow

Well can you explain this imagine for a beginner to this concept?

#

Or what can I look for to learn this

spice hornet
dark sparrow
#

look up "SOH-CAH-TOA" and "trig values of special angles" maybe??

#

i am referring directly to the defn of trig functions

spice hornet
wicked tartan
#

This is all I got from the teacher I need to find the distance of BD

upper karma
wicked tartan
empty yew
digital egret
#

yikes

upper karma
#

This is the cutest math I have ever seen.

#

Bro if this comes on my exam, I would rather fail

upper karma
upper karma
#

Dude

#

The thought that smth like this even exists

#

Itself is frightening.

upper karma
#

Am in grade 9 man 😭

#

Through I would still interested to see what went wrong

upper karma
#

Nvm dude

#

I can't even solve simple side change maths

#

I mean… I know I messed up, but like this thing only required like grade 7 geometry and thats it. But problems can get a bit difficult in geometry, like this one which was meant for some high schoolers:

winter garden
#

can u bring back the old message

#

i was looking at it

#

please

winter garden
#

Why was that a reply message idk

#

Accident

upper karma
winter garden
#

4 X 30 = 120

#

Why is it cap

#

Nvm gotta go rethink

rugged shuttle
upper karma
#

Oi oi oi

#

What's going on in trigonometry???

#

Speaking of trigonometry

#

I am very bad at trigonometry and geometry in general

arctic vector
#

Could someone help me with geometry?

dark sparrow
#

!da2a

lime crownBOT
#

No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/

past geyser
#

just post the question, no need to ask for someone to help you

arctic vector
#

Idk how to translate

#

Let me translate ir

#

Based on the drawing, calculate the area of ​​the shaded quadrilateral

#

@past geyser

past geyser
#

have you heard of the pythagorean theorem

#

@arctic vector

arctic vector
#

Yrd

#

yes

#

But im confused

#

Where to pit then umbers

#

And how to do the calculations

dark sparrow
arctic vector
#

Lithuanian

dark sparrow
#

ok nevermind

#

right so you want the area of this, ok

#

let's maybe start by giving names to all the relevant points here.

#

gimme a moment to reproduce this shape.

arctic vector
#

So yeah

dark sparrow
#

ok so here is the thing

#

i gave names to all relevant points and reproduced all of the markings from the diagram.

arctic vector
#

Alright

#

I i olny know where the rectanglr is

#

That at the top and botton should be 2

dark sparrow
#

the shape consists of 3 pieces, and we will proceed by calculating the area of each one:

  • triangle CED
  • rectangle BCEF
  • triangle ABF
dark sparrow
#

i gave names to everything, specifically to avoid these vague terms of location.

arctic vector
#

If im right

#

It should be like that

dark sparrow
#

ok but can you name these two segments?

arctic vector
#

Wdym

dark sparrow
#

also wow, black bands.

dark sparrow
#

as in

arctic vector
dark sparrow
#

they do have names, i want you to say their names.

arctic vector
#

Hard choicr

dark sparrow
#

"hard choice" means you either don't know or don't remember what i might be talking about.

arctic vector
#

Im terrible at math

dark sparrow
#

if a segment has one end named P and another end named Q, what is the name for the segment itself?

arctic vector
#

I cant tell it in english

#

I dont know hoe its called in english

#

How

dark sparrow
#

it's language-independent, i would say.

arctic vector
#

yes

dark sparrow
#

such a segment would have the name PQ.

arctic vector
#

Oh

dark sparrow
#

segments are named after their endpoints in just this manner.

#

always.

arctic vector
#

Ohh

dark sparrow
#

this is why we give names to things.

#

names to points more specifically.

#

so that we can refer to segments, angles, polygons etc. unambiguously via their names

#

and everybody can tell from the diagram what lies where.

#

understood?

arctic vector
#

50/50

#

Let me translate it

dark sparrow
#

too bad i don't speak lithuanian.

arctic vector
#

Ohh

#

Yes

#

I understand

dark sparrow
#

alrigt

#

alright*

#

so yes, BC = FE = 2 cm, you are right about this.

arctic vector
#

Just nor sure where to get the orher 2

dark sparrow
#

now for what comes next, i'll need you to follow my instructions closely.

arctic vector
#

okay

dark sparrow
#

and i also need you to NOT do something i didn't ask about.

arctic vector
#

Ok

dark sparrow
#

ok

#

look at this diagram now, and focus specifically on triangle CED.
you will be applying the Pythagorean theorem to this triangle.

i want you to fill in each blank space in the following formula with one of the sides of this triangle (CD, DE, and CE):

____^2 + ____^2 = ____^2

  • You must reply with the entire formula, with the blanks filled in.
  • I will reject an answer that consists of just the three sides listed with commas between them; for example, the answer DE, CD, CE or anything similar will be rejected.
  • I will reject any answer that contains any numbers (aside from the 2 exponents); for example, the answer 2^2 + 3^2 = CD^2 or anything similar will be rejected.
arctic vector
#

Okay

dark sparrow
#

ok, awaiting response.

arctic vector
#

So wait

#

Oh nvm

#

Got it

dark sparrow
#

awaiting response!

arctic vector
#

I dont have a calculator by me so ik doing it in website

dark sparrow
#

no

#

you do not need a calculator for this.

#

do NOT do anything with the equation, except what i am asking.

arctic vector
#

Yes i know

dark sparrow
#

you can and should write it here in plain text.

#

^

#

if you need this symbol

#

it is most likely shift+6 on your keyboard.

arctic vector
#

Im on phone

#

Difficult for me haha

dark sparrow
#

i believe in you.

arctic vector
#

So if it’s not √ 2^2 plus 3^3 = ?? then how should it be?

#

Thats how my math teacher does it

dark sparrow
#

sounds like you didn't read my instructions!!!

#

I will reject any answer that contains any numbers (aside from the 2 exponents); for example, the answer 2^2 + 3^2 = CD^2 or anything similar will be rejected.

arctic vector
#

Im confused about that

#

Do i have to take out the square root too or what

dark sparrow
#

no, no square roots.

#

ok, let's go back one step.

#

since you aren't great with english mathematical terminology (which is perfectly understandable),

dark sparrow
#

no, forget the numbers!

dark sparrow
#

since you aren't great with english mathematical terminology (which is perfectly understandable),
let us go over the relevant words for our scenario.

#

first,

#

do you know what the word "right angle" means?

arctic vector
#

I think so

dark sparrow
#

ok.

#

so you know that a right triangle is a triangle in which there is a 90° angle.

arctic vector
#

Yes

dark sparrow
#

(and there can be only one. there cannot be two.)

#

ok.

#

now

arctic vector
#

Yes

dark sparrow
#

two of the sides of a right triangle are touching the right angle, while the third side is across from it.

#

do you know what the side across from the right angle is called?

#

it's ok if you don't, i will tell you. but i want to see if you know.

arctic vector
#

Let me translate

#

I dont know.. half of the angle?

dark sparrow
#

no.

#

it's called the hypotenuse.

#

the side across from the right angle is called the hypotenuse.

arctic vector
#

Oh

dark sparrow
#

and i'm also going to say that the other two sides, which are touching the right angle, are called the legs.

arctic vector
#

Ooh

dark sparrow
arctic vector
#

Yeah

dark sparrow
#

i can look up the translations of these into lithuanian if you want.

arctic vector
#

Inunderstand

dark sparrow
#

ok, right.

#

now that we that in order,

the Pythagorean theorem states: the square of the hypotenuse equals the sum of the squares of the legs.

#

in other words, (leg)^2 + (other leg)^2 = (hypotenuse)^2.

#

these might be named by different letters, so i am avoiding the usual presentation as a^2 + b^2 = c^2, and on purpose.

arctic vector
#

Oh

dark sparrow
#

so coming back to this

#

applying the pythagorean theorem to triangle CED

#

you would have:

CE^2 + ED^2 = CD^2

#

understand?

arctic vector
#

Yes

dark sparrow
#

ok.

#

so now we can fill in the numbers that we know

#

namely that CD = 3 and ED = 2 (as given to us directly)

#

which gets us:

CE^2 + 2^2 = 3^2

#

can you find CE now?

arctic vector
#

Pythagorean?

dark sparrow
#

i don't understand your question.

arctic vector
#

Ce by pythagorean?

dark sparrow
#

with all due respect, have you been listening to all the things i've been saying?

arctic vector
#

Tes

#

Yes

zinc reef
#

@arctic vector

dark sparrow
#

you have the equation

CE^2 + 2^2 = 3^2
yes it did come from the pythagorean theorem.

arctic vector
#

Yes

dark sparrow
#

but now it does not matter.

#

you just solve it like any other equation.

#

for that, its origin in the theorem doesn't matter.

zinc reef
#

The Pythagorean Theorem was created by Pythagoras

arctic vector
#

Oh

dark sparrow
#

do not overthink. just do what i tell you.

arctic vector
zinc reef
#

It can solve world problems

dark sparrow
#

why are you doing math while sleepy?

zinc reef
#

a2 + b2 = c2

dark sparrow
#

are you doing homework for tomorrow morning?

dark sparrow
zinc reef
#

No

arctic vector
zinc reef
#

I study pre university math

arctic vector
zinc reef
#

I literally do math for fun

arctic vector
#

Most people are only obline late

dark sparrow
#

are you in grade 5?

#

are you over or under 13 years of age?

zinc reef
#

You are acute

dark sparrow
#

i repeat @tame gale are you over or under 13 years of age?

#

ok

#

anyway

#

@arctic vector do you want to continue?

arctic vector
#

Mhm

zinc reef
#

@dark sparrow Can I join

arctic vector
#

What the

upper karma
#

Umm

dark sparrow
#

discord's TOS forbid users under 13 years old.

upper karma
#

Kiarny

#

That was a bit too much.

dark sparrow
#

<@&268886789983436800> user kiarny was seen posting a decidedly inappropriate gif.

#

which has since been deleted.

upper karma
#

Nice joke dude

#

I was 14 2 weeks ago

arctic vector
upper karma
#

Ahh

#

You know abbreviations such as "idk"

#

But don't know English.

#

Very interesting.

zinc reef
#

@arctic vector Can I join whatever you and Ann were doing, I'm certified Mathlete

arctic vector
#

mhm

dark sparrow
#

again

#

you have the equation

CE^2 + 4 = 9
in front of you

#

find CE.

zinc reef
#

Why

dark sparrow
#

you will obstruct more than you can help.

arctic vector
#

Howwwwww

zinc reef
#

I'm a thirteen year old prodigy in highschool and I study university math and physics

dark sparrow
dark sparrow
#

i cannot tell you this in any other way except by doing it for you.

zinc reef
#

Not like assistance, it's that I'm lonely and no one wants to be my friend

arctic vector
dark sparrow
dark sparrow
#

no, not even close.

arctic vector
#

This is how bad i am

zinc reef
#

Not chat talk about math

dark sparrow
#

but here you are just getting in my way.

arctic vector
#

I need tons of examples just for me to understand

dark sparrow
arctic vector
#

Yea

dark sparrow
#

i think it will be very difficult for us to progress here.

#

are you able to come back to this problem tomorrow?

zinc reef
#

No one pays attention to me because they think I'm crazy because I'm trying to solve Raymon's Hypothesis

arctic vector
#

yes

zinc reef
dark sparrow
#

<@&268886789983436800> we got a refusal to comply with redirection here

zinc reef
#

Okay fine

#

I'll go away

#

I'm sorry

arctic vector
#

@dark sparrow do we move this to tmrw

#

What time tho

dark sparrow
#

you're the one with the problem

#

come back here when it's convenient for you

arctic vector
#

Ok thx

dark sparrow
#

i can't and won't guarantee that i will be available

arctic vector
#

Yes ofc

#

Ok bye

zinc reef
#

@dark sparrow

dark sparrow
#

yes?

zinc reef
#

Why are you so mean

dark sparrow
#

in what way was i mean? by redirecting you while you were interrupting a convo with somebody else?

zinc reef
#

I said I wanted to join your conversation because I was curious

dark sparrow
#

the way you inserted yourself into the conversation was by repeating things i said earlier.

zinc reef
#

On what math equation you were talking about

dark sparrow
#

the conversation also had a purpose -- helping mm2swifty with his geometry problem -- and you got in the way of that.

#

i do apologize for being rather crass in telling you off.

zinc reef
#

I accept

dark sparrow
#

you try walking up to someone irl who's having a convo and interrupting them though -- i imagine they won't be very happy about that

zinc reef
#

I do imagine a lot of crazy things like in physics I imagined a blackhole curving the spce and time around it like Einstein

zinc reef
#

They think I'm crazy

upper karma
zinc reef
#

What do you mean

upper karma
#

It's a joke

upper karma
glacial dawn
blazing veldt
glacial dawn
#

ye

dark sparrow
#

uhh

#

does it tho.

dark sparrow
#

yeah, no, it doesn't.

blazing veldt
somber coyoteBOT
#

Primordial

dark sparrow
#

but you aren't saying the equality tan(A) = 3tan(A)/(1-tan(A)) - 1 holds for all A, are you?

#

(which indeed it doesn't)

dark sparrow
blazing veldt
forest blade
#

Are there any good videos that go over double angles and half angles and explain what is happening well so you understand the concepts?

#

I just had an exam and feel like I'm struggling to figure out anything involving half angles

#

And I hate continuing to the following sections when I didn't feel good about the previous sections. I feel like it just builds a bad foundation :/

rugged shuttle
forest blade
jagged wyvern
#

Can someone tell me why this is 10.1, and not 9.9?

I used Tan^-1(3.5/20)

3.5 is the height (O)
20 is the base length (A)

cunning lion
#

are you sure 20 ft is the base length?

jagged wyvern
#

Uhh

#

Ohh i see it now

#

Sin^-1 was suppose to be used because it says surface of ramp so hypothenuse

#

🤦‍♂️

deft sail
#

The line length in 20

#

I see 4 of 1/4 circles

#

I’m confused

oblique wadi
rugged shuttle
faint comet
#

Yo guys

#

For the equation like this without the pi/4 the y inter is 0 but since it has the pi/4 I know the y inter is going to be higher how do I calculate the exact vaule of that

dark sparrow
arctic vector
#

@dark sparrow hi

oblique wadi
#

what does it mean to have a y-intercept in the xy-plane?

faint comet
# oblique wadi read their question

My question is I know how to calculate the y-inter for sin which is represented by D, so I am asking how would calcite the y inter for sin when their is a horizontal transformation.

oblique wadi
#

look

#

you can set $f(x)=\sin (x+\frac \pi4)$

somber coyoteBOT
#

Kakaka

oblique wadi
#

do you know what a y-intercept is?

#

for a function

faint comet
#

Bro just answer my question lol idk why your being a prick

oblique wadi
#

in your original questoin

#

why does it matter what the horizontal shift is?

#

$f(x)=\sqrt2 \sin (\pi/4)$

somber coyoteBOT
#

Kakaka

dark sparrow
#

please edit that word out of your message.

oblique wadi
#

xD

dark sparrow
oblique wadi
#

oops yes

faint comet
oblique wadi
#

sin π/4 = √2/2

#

from unit circle

faint comet
oblique wadi
#

you don't actually understand what a y-intercept is

#

hence your confusion

faint comet
faint comet
oblique wadi
#

do you see your problem here

dark sparrow
#

@faint comet please edit the word "bro" out of your earlier message.

oblique wadi
#

I initially tried to direct you to think about the precise definition of the y-intercept to help resolve your confusion

dark sparrow
oblique wadi
#

but you ignored me

oblique wadi
somber coyoteBOT
#

Kakaka

faint comet
dark sparrow
#

@faint comet i repeat: please edit the word "bro" out of your earlier message as i asked you 3 times now (incl. this one)

faint comet
#

Bro that’s so mean

dark sparrow
#

<@&268886789983436800> we got a deliberate misgenderer here

#

maybe 2 if we also count detakro

faint comet
granite mortar
#

i think detakro was referring to archer