#geometry-and-trigonometry
1 messages · Page 20 of 1
I think this is a fine way to use chat gpt actually
As long as you verify after the fact (which is what I'm doing now)
This kind of definition-to-name is exactly the kind of thing that Google is bad at
Each side is length 2 in this cube though
Well if every vertice was (+- 1, +-1)?
Well you'd have a cube whose centroid is the origin
In simple terms
Right
Now if you google "alternating cube" a bunch of Rubik's cube ads pop up
So idk where it's even getting that info
It probably hallucinated it
There's probably something else called the alternating something
That's \pm 1 over and over, idk what it would be
idk what this is but anyone know this one?
it has something to do with combination and permutation
your question belongs in #discrete-math
find critical points and use first derivative test ?
nvm that would be calc way uh i think best way might be to graph it if thats allowed
ok thanks
8sin A - 6cos A=?
The value of A should be such that the answer of equation is highest
Also y^2 is indirectly proportional to x^3 graph
Alr
geometry is kinda hard
Draw the figures
A chord is a segment that connects two endpoints that are on the circle.
Let O and G be the centers of each circle
Notice how OA, and OB are the radii of circle O because they connect the center to a point on the circle.
The radii of the same circle are congruent. This means:
but
Yup for âłAOB
why not for GCD tho
Now if you notice that GC and GD are also radii of circle G, you get:
âłCGD is also an isosceles triangle
ohhhh
but how does that help us find out
if the arcs are also congruent
cuz we dont know the values
So arc AB is intersected by chord AB, right?
yeah
And arc CD is intersected by chord CD
mhm
The measure of the arc is equal to the measure of the angle is subtends or "bounds"
So this means that mâ AOB = measure of arc AB
And mâ CGD = measure of arc CD
So we just need to find out if mâ AOB = mâ CGD
Nope that's an inscribed angle
â AOB and â CGD are central angles
You see here
â ABC is half the measure of arc AC
â ABC is an inscribed angle
An inscribed angle is an angle formed by two chords and has its vertex on the circle
And you can see here
mâ AOB = measure of arc AB
â AOB is a central angle
A central angle is an angle formed by two radii and has its vertex on the center of the circle
Do you understand now?
so that arc/2=angle thing doesnt apply for central angles
Right. Only for inscribed angles
okkk
so anyways
so arc AB= Angle AOB and Arch CD = Angle CGD
but is arc AB = arch CD??
We will find out if you can prove that mâ AOB = mâ CGD
since mâ AOB = measure of arc AB
and since mâ CGD = measure of arc CD
You can do it if you can first prove that âłAOB â CGD
There are 5 ways you can prove triangles to be congruent:
SAS (Side-Angle-Side) â
SSS (Side-Side-Side) â
HL (Hypotenuse-Leg) â - only use for right triangles
AAS (Angle-Angle-Side) â
ASA (Angle-Side-Angle) â
So are you familiar with proving triangles to be congruent?
i think so yeah
Alright
ofc
i dont want to disturb you but I also had this question on my mind im not sure how to do it
đ
Using Tangent Secant Theorem
12^2=7(7+x)
144=49+7x
95=7x
x=13.57
And round it to the nearest tenth
So it'd be 13.6
Here's a picture of the tangent secant theorem xrayne referred to:
how come the arc measures are not congruent if the radii of both circles are congruent, so is their chords?
cant it be proven using SSS criterion?
Can someone help pls
The question says that the two circles have different radii đ
yeah, but i didnt get why you illustrated the two circles as having congruent radii
No I didn't
You see here
The radii for circle O are OA and OB. OA = OB.
The radii for circle G are GC and GD. GC = GD.
OA â GC, OA â GD, OB â GC, OBâ GD
help đŠ
first find the areas of the circle and rectangle
which would be
area of circle = 28.27(28 approx.)m^2
area of rectangle = 216m^2
probabilty = 7/54
that would be option 2
how did u find the area of the circle
ohw ait nvm
but once i got the area what do i do from there
the area of the rectangle is 216 and the area of the circle is 28, as concoran_edmund said. the point P is gonna be certainly placed in the rectangle and the circle only covers 28/216 m^2 of the rectangle, so there is 7/54 chance that the point P will be placed within the circle
isn't 1-sin^2x equal to cos2x already?
it is
but what should i do next
I thought it was easier tu substitute 1-2sin^2x with cos^2x-sin^2x
I'll try to do it but it probably doesn't have a easy solution sadly
so its gonna be a bit painful
ok ty lol
maybe we can do it from the square difference formula?
will be equal to cos2x itself
ill do us a favour and turn that image sideways
okk
plus it wouldnt let me download it
heree
i don't see difference of squares here tho
oh damn wait
ok I have seen something wrong
that doesn't work
I thought of the 2's like they do not affect the square
that's funny, I've never seen those formulas before lol
and thats equal to cos2x
same but I think its not gonna give anything I believe since sin2a*sin2a is sin^2 4a and not sin^2 2a
the own formulas itself still are painful tho
the funny part is that the textbook where I found the equation didnt mention those formulas
idk how they expect me to solve it lol
maybe there is another way that we don't see?
probably
but I can't see any other way doing it without the formulas
hmm if its -cos4x = cos2x
maybe we can write -cos2(2x) = cos2x
so does that make -2cos^2(2x)-1=cos2x
-2cos^2(2x)-1-cos2x=0
-(2cos^2(2x)+1+cos2x)=0
I was trying to find a smiliar question and found the equation for cos4x=cos2x
can it lead to somewhere?
lmao
ohh
I can ask my teacher tomorrow, thanks for trying to help tho
yw but still sending these just in case it can help
by the way if you guys solve it tomorrow, can you also send it here I am really curious lol
yeah sure
thanks a lot
<@&268886789983436800>
that looks hard
try finding the coordinates of the vertex
what is g(x)=?
idk why they posted it here but it's not trigonometry
this? @snow crystal ?
yeah
oh damn I really did not notice that I sent it here Im sorry
but I already sent it to a friend so I guess there is no need for help
still ty â€ïž
yw
ew
@upper karma turns out you can substitute sin^22x with 1-cos^22x and you get a quadratic formula
I have finally finished my trigonometry assessment
I can finally finish up for the night and sleep
Does anyone know how I can determine the area of this figure?
i really forgot how to do it and my friend is asking me for help with it
Try dividing it into smaller figures
couldn't manage to
is this the only pic you have of it
also should we assume everything that looks like a right angle is one
also is that an actual textbook exercise or did you think it up
not all side lenghts are given too
<@&268886789983436800>
<@&268886789983436800> spammed advertisement ^
?
?
<@&268886789983436800>
Geometry is pretty easy if you compare with algebra 2 and other algebra classes
But I still prefer algebra than geometry
âProof me why is this a triangleâ

3 sides motherfucker you can count them. One, two, fucking three
Gonna prove my teacher why his wife divorced him
bro...
geo so hard
eh both are equally easy
hello guys
im in class 8
is there any good book
i can practice trigonometry from
i'm not required to take trig so i never took it so i'm not sure
You can just google worksheets . There's plenty of challenging as well as easy ones in those online worksheets .
What exactly about geometry do i need to know or would i be fine if i skipped geometry and went straight into algebra 2? The goal is to be ready for pre-calc/calc
i wanna know too
Hopefully we find outđ«Ą
đ«Ą
i took algebra 2 first and then geometry
i prefer taking algebra 2 first than geometry
because algebra 1 skills can be used in algebra 2 even though i think algebra 2 is basically the same as algebra 1 but i think if you took algebra 1 ( honors ) then algebra 2 would just be a easy class for you to take.
Ive graduated not too long ago but i had no idea what i wanted to do for my future, now im going to college for comp sci and im currently trying to catch up on math but idk how badly i need to relearn/know geometry for pre-calc/calc 1
dam
that's tuff man
computer science is pretty good
i'm taking business class so i have to learn about math in business
Yeah
Especially when they want you to proof it in a paragraph
Is like another English class
Use your eyes

We did flow chart proofs and paragraph proofs and 2 Column proofs
Oh okay I need a magnifying lens then
All my homies hate proofs
You need to write soo much is crazy
Is not hard to understand the thing is different subject have different proofs
And you want us to remember all that and they be like you can build a house with geometry

Cya
uh
this might be stupid but
if pi is an infinite number
wouldnât it be true that there is a 100% chance that there is an infinitely long chain of 0s
which means itâs a constant
If that were the case, pi would be rational, at some ratio with an arbitrarily long numerator and denominator, but it is possible to prove pi as being irrational
Pi is nonetheless still a constant
Pi never changes according to some variable
It is simply a number
Even if it is irrational
I see
can someone teach me the aspects of geometry
cuz i am preparing myself
for the finals
Guys, In triangles is there a relation between the orthocentre and and its vertices which shows the type of triangle(equilateral, isosceles, scalene )?.
The location of the orthocenter can help you determine whether a triangle is obtuse, acute, or right
Uh but I do I know what in equilateral triangles, the orthocenter is also it's centroid
@manic hollow
As far as isosceles and scalene triangles go, not too certain
irrational*
It's a constant anyway since its value never changes
Oh I didn't read this sry
I don't think u can prove a number with this property is finite
How would you find a tangent line at a sharp corner of a curve that only intersects the point at the corner? If not the tangent line, then a line that behaves at described
It's not always possible:
fair, I guess im looking at something more like this, blue representing the tangent line I'm getting at the moment
ahhh
if you know the curve is smooth to the left of the point (or the right) you could calculate the left-derivative of the curve
or the right depending on the side
like if you look at f(x) = |x|
the left derivative at x = 0 would be -1 and the right would be 1
would the output of that be something similar to the blue line depicted:
no, it would be like your first picture, basically the direction the curve is headed if you approach the sharp point from the left or right, the problem is that if the curve is sharp there's no real way to get a "tangent line" at that point, precisely because there's no derivative at that point
you could do some things like take the average of the left and right derivatives, but that won't always give you what you want, since curves with a point don't have tangents at that point
Just put a normal over everything and hope for the best
not possible most of the time
theres a physics phenomenon which also
explains how u cant find the direction of normal force from an edge
which is kinda similar that ur looking for tangent lines
thats why an absolute value graph is not differentiable for all values of x
bc of the (0,0)
Understood thanks for the help!
Can't. You'd have an infinite number of tangent lines. And we hate infinity
That's the easiest way to describe it
The moment a mathematician rotates 8 90°, they start shitting themselves and screaming
wat
does that mean
Good question
Can you divide a square into 3 equal area triangles?
!status
What step are you on?
1. I don't know where to begin
2. I have begun but got stuck midway
3. I got an answer but I'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
Why do they hate infinity?
Infiniteez nuts
Nah but when it comes to tangent lines
By definition there only should be one locally
At corners you'll have an infinite number of tangent lines
Anyone able to help?
What step are you on?
1. I don't know where to begin
2. I have begun but got stuck midway
3. I got an answer but I'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
@storm grotto What do you need in order for a triangle to be isosceles?
2 equal sides and 2 equal angles
no just one
its an if and only statement
so u only need one to prove the other'
Yeah, those both have to be true but if you show one then the other has to be true
Sorry I misread it anyway. They've already given you the steps of the proof, you just need to label each step
I'm guessing you have a textbook that gives you names for the different rules you can use in a proof
can I ask about vectors here đ
that goes in algebra, ig
no they are linear algebra
hmm
Is there some Chinese in this group,i want help
With a math video that is in Mandarin possibly
It's the only video on that topic that i can find.....
https://youtu.be/AP8Wvn9X6v8
This is the video
The time duration where i need clarification is from 15:00,from 25:45 and from 27:20...
Here he discusses
1)Some Rhombus sort of structure,i want to know with what arguments did he arrive at that conclusion
2)He talks about Cauchy Crofton Formula,what context is he talking about it.....(like why is using that there),i have rough idea of what Crofton Formula is...
3)third in 27:20 one,He talks about evaluating integral(it comes up in his slides) integral(1/(1+x^3)) how does it come up there
Help with these,even if you can just translate and type what he said,i would be very thankful
<@&268886789983436800>
Depends on what you do with them
Many geometric theorems with vector in R^2, but if you have a question that involves vectors in an algebraic way then algebra channel
guys I'm lost, what am I doing wrong here??
The sum to product thing doesnât work because thereâs a sqrt(3) attached to the left term
so what can I use instead?
You need some other observations to solve it
Consider writing sqrt(3)cosx + sinx as 2sin(pi/3)cosx + 2sinxcos(pi/3)
Then use compound angle formula in reverse
i need help
Send me math problems to solve so I can get better and better!!! :)
@wooden patrol are you still there?
I'm having trouble with analytic geometry
look
Do any of you get it?
Not sure why you need to use vectors and linear algebra to prove triangle OAB is equilateral
if e1 and e2 are unit vectors with an angle of 60°, it should be easy to prove that AOB will be a unit equilateral triangle
how did you get D?
so
I did 12x+8=10x+15
and the -10x so it became 2x+8=15
and then i subracted 8
so it was 2x=7
then divided by 2
so it was x=7/2
then i plugged that into the equation
and got 50
wait so is the answer C?
someone pls help
what equation
sorry for the delay on my part -- was busy
it's okay
12+8
12x*
i plugged it in 10x+15 too
and got the same answer
yes, so that way you know your x value is correct
note that the two sides of the equation 12x+8=10x+15 are AM and MB
you are asked for AB
okay what do i do next?
@dark sparrow C was wrong, so is the answer D?
the answer is A nvm
no, it is not.
in fact you had the right answer the first time round
you just could not justify it properly
so D is the answer?
but I'm still confused
how did we get 100?
we got x = 7/2
we got AM = 12*7/2 + 8 = 42+8 = 50
thus also MB = 50
AB = AM+MB = 100
how do i find the answer to this
someone please help me
i have 5 mins before the assinment is due
pythagoras
is that a^2+b^2=c^2
ye
that's for you to figure out
okay thanks
help
the laws of sine / cosine are to be used when you're not working with a right angled triangle, right? otherwise you work with the whole sohcahtoa thing right?
Yea for right angled triangles you can just use the ratios of the sides to the angles (sohcahtoa)
Someone help please, Iâm not sure how to do the second and third one
For 2 you should first find the length of the bottom side in the top picture
The âends at the same point on the groundâ part and then just use Pythagorean thm
3 is similar
Alright, thank you!
did i do this right?
yea
In the isosceles triangle ABC, B=120 CD is the height of the triangle,
Find AD if the length of the altitude through the vertex B is 10.
<@&286206848099549185>
Another programmer nice XD
Sure
In isosceles triangle ABC:
- B = 120 degrees (angle at vertex B)
- CD is the height of the triangle
right?
Yes
We're also given that the length of the altitude through the vertex B is 10 units.
Yes
Let's denote this altitude as BE, where E is the point where the altitude intersects side AC.
Sure
Now, since the triangle is isosceles, we know that angle A = angle C. Thus, angles A and C are equal.
Yes
Let's denote AD as x (the length we need to find). To find AD we need to determine the relationship between x and the known lengths in the triangle
AND
Since CD is perpendicular to AB, angle CDB is a right angle. Angle CDB = 90 degrees.
right?
Yes
Since angle CDB is a right angle and angle B is 120 degrees we can find angle C using the following equation:
angle C + angle B + angle CDB = 180 degrees
angle C + 120 + 90 = 180 degrees
then solving we get angle C = 30 degrees
as angle C = 180 - 120 - 90
right?
Lol
yea but how
error in the statement?
I don't think so
đ
I am dumb too
lemme open a help channel
I am dumb three
Lol i found AD
W
can someone explain me this
in both cases the 2 planes are cutting the same quadric if im not wrong
no idea but u should help me #help-2
pls help idk how to do this
have a read on inscribed angles and central angles theorem
I dont understand how the top equation can be turned into the lower equation. The video im watching attempts to explain the concept called a "Perfect square" I dont see how that applies here.
First of all, that's an expression, not an equation.
if you had to turn the lower expression to the upper one, could you do it?
I can understand the X squared and the lone four; but I dunno where the 4X came from. sorry for the wrong vocabulary
Do you know how to expand something like (a+b)^2?
(It is not the same as a^2 + b^2)
well- what about (a+b)(c+d)? How would you expand that
wouldn't you multiply cd by a and b then like add or smt?
can you try it? Like write out the expanded form of (a+b)(c+d)
if you cant do that then there is quite a lot of catching up to do
I dont remember being taught this bud
its in a geometry problem nvm
In the triangle ABC, the line AD is perpendicular to the median BM and bisects it.
Find the length of side AB if MC =10.
<@&286206848099549185>
excuse the bad drawing
10 is good but it's wrong XD
Answers are
A)2
B)3
C) 5
D)8
i tried and got 10 as well , but i might just be bad at geometry, ill draw it one sec
I also got 10
since BM is the median, it dissects AC into 2 equal parts AM and MC, so AM = MC = 10
BO = OM, because AD is perpendicular to BM and bisects it at O
Triangles BOA and MOA share the side AO, and BO = OM and the angle between them is equal (90 deg)
so they have 2 equal length sides and the angle between them is also equal, therefore the remaining sides AB and AM are equal, so AB = AM = 10
sorry if this was worded badly, first time actually trying to explain anything in math in english
tried ,y best to make the drawing fit too
Am will be 5
AC=10
you said MC = 10
Done XD ty
no worries, happens
(x+2)^2= (x+2)*(x+2) , you can write like that: (x+2)*x + (x+2)*2 = (x^2 +2x) + (2x + 4) and here we come to x^2 + (2x+2x) +4 = x^2 + 4x + 4
How would you go about finding DEG in this photo
đ DEG = 31*
Thank you I see now
can someone help my friend with this question
v: Angles on a straight line always add up to 180Âș, so 30Âș + v = 180Âș, v = 150Âș
y: Angles 30Âș and 2y are called alternate interior angles, because they lie on the opposite sides of a line that is passing through two parallel lines, they are equal. 2y = 30Âș, y = 15Âș
z: Angles on a straight line always add up to 180Âș, so z + 130Âș = 180Âș, z = 50Âș
w: Angles 130Âș and w are called co-interior angles, because they lie on the same side of a line passing through two parallel lines, they add up to 180Âș. 130Âș + w = 180Âș, w = 50Âș
x: Angles on a straight line always add up to 180Âș, so x + w + 2y = 180Âș, x + 30Âș + 50Âș = 180Âș, x = 100Âș
tysm!
!nosols
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.
tell your friend to come here and ask for help herself
my bad my bad i thought it was better to explain stuff but that makes sense
Would it have been better if i just said the answers? should i also give the rules used to find the answers, but not tell them in which steps exactly the rules are used?
Have the student work through the problem themselves and guide them along the way.
avoid giving answers if possible
right, so i should've just explained the rules that were used in the solution, but not where to use them
My bad, I'll know next time
progressively go into more detail as needed
question their understanding of rules, clarify rules if needed
see if they are able to identify where they're applicable
direct them to where to apply them if required,
alrightt
can someone help with this?
just wondering is there is the a way to expand tan(a+b)
similar to expanding sin(a+b)
yes tan(a+b) is simply sin(a+b)/cos(a+b) now simplify this to get it in tan form
[tan(a) + tan(b)]/1-tan(a)tan(b)
like as a religion or?
why do ppl like math so much smh
Something that came out of our heads and describes the universe, is deeply mesmerizing
bro math is just like every other religion, it explains natural phenomena
We are just crazy
oh yeah completly forgot about that
In the first one, apply the formula s = rΞ
ya I'm struggling w b
Wdym?
Anyways, to get through the 2nd one firstly u have to get the area of AOB and the area of AOC triangle individually
Then summing it all up would give the desired solution u r looking for
For the AOB
Apply (Ξ/360)* Ïr^2
For the triangle,
Draw a perpendicular from A to CB and use sine to get the height of the perpendicular
Then Apply the normal formula for triangles.
@upper karma
U r welcome
saw this fun highschool lvl problem online im pretty happy to have solved it and thought to share it to yall
I got 36Ï-56sqrt(3), is that the answer?
close, but nope
oh right!
,rotate
6*9 isn't 56
there you go!
so it's 36Ï-54sqrt(3)
ohh ight. lol my handwriting is no better eitherway
how was the problem?
I did something similar a couple of months ago in school
so it wasn't THAT hard
This is what we did
,rotate
10th
the 10th grade textbook I have doesnt have those
you're in college?
nah I'm in high school
oh lol
idk I'm from Poland so it probably looks different from your school
but basically we choose 2 subjects that we're going to major
in high school
you take the exterior angle
wait no
exterior angle is 18
divide by 360
360/18=20
do you know how you can find the interior total angles of a polygon? (for example the angles of a triangle)
correct
Where n is the number of sides
so if we divide it by n, it means that each angles is 172, right?
Divide what by n??
this formula
(n-2)*180/n = 172
now try to find n
yes, multiply both sides with n, which will give us, (n-2)*180=172n, therefore 180n - 360 = 172n
now find n with this equation
move 172n to the left side of the equation and 360 to the right side, we will have 180n-172n=360
8n=360, n=45
I started with SL loney's plane trig book.
I needed a bit of advice on whether the ones who solved it solved all the questions and how much time it took them to finish the book
The sum of all the exterior angles of a polygon is 360
So 360 = 8n
So n=360/8
I apologise for being a dumb as
n=45
Ye
guys how do I do this
do you know your parallel line theorems
and/or have access to a list
- x=70 alternate angles are equal
- x=130 Vertically opposite angles are equal
IDK about 7 and 9
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.
Use parallel-transversal laws
idk what they are
I know a bit about them
ohhhh
x=130 is number 10
Just post it
I did in the help-forum.... no one helped
anyways
Prove that sin pi/14 is a root of the equation 8x^3-4x^2-4x+1=0.
This is the question
I would be grateful if u could help....
Ok so you have to substitute x with sin pi/14 and see if it's equal to zero
I did... but the equation is becoming too lengthy... and nor am I able to simplify it
Basically when you have such equation and want to check whether certain number is its root you have to substitute x with the given number
Hmm
could u just tell how I can simplify it?
,rotate
hmm
so these are the roots...
and I basically replace x with sin pi/14 and check right?
Yeah
I Don't have time rn but try to plug in sin pi/14 and find some trig identities/formulas that will help you to simplify the equation even more
ohh ok... thanks
the only time you can use the sine rule is when you have two angles + a side opposite one of the angles or two sides + an angle opposite one of the sides right?
When you're given two angles and one side of a triangle
Or, when you're given two sides and the opposite angle to either one of the sides
Alternatively, when you're given one side of the triangle and the radius of the circumcircle
(Or one angle and the radius of the circumcircle)
" when you're given two angles and one side of a triangle "
the law of sine wouldn't work if you have angle A, angle B and side c bc you need atleast one angle and it's opposite side for the law of sine to work?
side a (unknown) / sin A (known) = side b (unknown) / sin B (known) = side c (known) / sin C (unknown )
unless the resources i've been using haven't explained it properly and i'm wrong
You can find angle C anyways if you know angle A and B
Because, A+B+C = Ï
-> C= Ï-(A+B)
This article has a detailed explanation for this type of question.
https://www.mbacrystalball.com/blog/2015/10/02/lines-and-angles/
oh thanks
11 is parallel, 12 is neither, and 13 is perpendicular. Did I do these right?
yes
okay thanks
what is the answer to number 4 and 6?
number 1 is alternate interior angles, number 2 is alternate exterior angles, number 3 is corresponding angles, and number 5 is corresponding angles
I can't figure out what 4, and 6 are
Q5 isn't corresponding
Q6 is similar to one of the ones you'd already completed
there's also a listed option you haven't selected yet,
if you're not sure what they are, its recommended that you look it up
what exactly do i search up
a listed option you haven't selected yet,
ohh okay
is it consecutive?
no
what
circle/highlight angles 1 and 8 on the pic
and compare that to your parallel line theorems
I'm talking about question 5 not 6
ohh okay
oh mb
it's a vertical angle
make sure you reply to the correct messages, i'm taking these at face value
1 and 8 aren't vertical angles
what are they, I'm so confused
circle/highlight angles 1 and 8 on the pic
and compare that to your parallel line theorems
wait is question 3 and 5 vertical?
okay
note that
Q6 is similar to one of the ones you'd already completed
and answered correctly
okay will note
Q6 is alternate exterior
yes
yea it made sense after
is Q4 alternate interior
I did but the pictures aren't like matching
what did you search up
Q4 is vertical right?
vertical angles, and consecutive interior angles
yes
ahh okay thank you for your help
How do I do 19
The two indicated angles add up to a right angle.
so is it 75 + (x+8)=180?
Is a right angle 180°?
In particular, does angle ABC in the diagram look like it's 180°?
no nvm i got confused with anoter question
so 90
Yes.
Yes.
Yes.
ahh thanks for the help
always remember that if two lines are perpendicular, then each angle in their intersection measures 90 degrees
anybody know how to do cross product on a vector of arbitrary dimension?
The usual concept of "cross product" only applies to dimension 3 (and in a somewhat different guise in dimension 2).
fair enough
In higher dimension there are different generalizations of the 3D cross product that preserve different of its properties, but none of them give you the whole package.
kk
was just curious cause i have implementations of it in my code for 2 and 3d, but was wondering if it worked in higher dimensions
not sure if this is the right place for this question but
i have a question that is relatively open-ended and vague
given the radius of this circle in blue
can anyone help me find a "natural" way to construct the line/length in red?
geometric constructions are fine, but i also don't want to limit myself to that, if anyone has any other clever ideas
can anyone tell me how we use trigonometry in real-life problems? Because I'm not sure how we use it though I know most of the concepts.
The most direct application is just the geometry
I have a wooden frame that is 3m by 4m, and in order to strengthen it, I want to add diagonal wooden beams connecting the opposite corners. However I need to know the angle of the diagonal beams so I can cut the ends accordingly. How would I calculate the angle?
These types of problems occur all the time in arts and crafts, construction, etc. Anytime you have enough information to determine the exact triangle, but you need the exact measurements of the sides or angles, you need to use trigonometry.
There are slightly more abstract usages, such as vectors, which are important in physics. Im pulling on a string in order to drag a heavy object up a ramp. How much strength is needed to pull this string? We can calculate this using vectors, but we will now need to apply trigonometry in the formula
There are also some much more abstract applications of trigonometry, but these are the kinds of topics that everyone here is excited to talk about so I'll let other people chime in on those
thank u
Hi I'm trying to prove $sin(\theta)= 2sin(\theta/2)cos(\theta/2)$
aSome1gussy
What I was given is đđđ=cos(đ)+đsin(đ)
with đ^đđ=(đ^đđ/2)^2
so what am i meant to do next
on second line (this "trick" yields De Moivre's formula).
idu how DM's formula relates to this, apart from maybe the modulus arguemnt form for r cis theta
are you not allowed to simply invoke the double angle identity for sine, of which this is an instance?
also
for a lot of it
perhaps, though, you could do this, for example:
let $z = \cos(\theta/2) + i \sin(\theta/2)$; acknowledge that $z^2 = \cos(\theta) + i \sin(\theta)$ by de moivre's, and expand $z^2$ the ``honest'' way and read off the imaginary part that results.
Ann
don't ping everyone
well, [cos(Ξ/2) + i sin(Ξ/2)]^2 = ?
you've got the square of a sum here, do you know how to expand that?
bru i'm legit tripping, can you do it for me
i'm literally caffeinated
ok i guess cos^2(theta/2)+2cos(theta/2)(isin(theta/2)-sin(theta/2)^2
r8?
ANQUAN AN NIE!
@dark sparrow
ye?
no
cos^2(theta/2)+2cos(theta/2)(isin(theta/2)-sin(theta/2)^2
yes
what was this about
sorry my pleas for help
isn't that contrived solution though?
SEEMS CONTRIVED
NAH?
OHHH i get it now ty
law of sines, if im trying to find a side then i should write the law as side over sin(angle) and if im trying to find an angel, i should write the law as sin(angle) over side. is that correct?
Thereâs no âcorrectâ way of writing that you âshouldâ use but if you find it easier this way then sure, go ahead
After all, itâs just the same fact written in two different ways
true
ngl trig is way easier than i remember from when i was school
ig i have a different mindsent now and actually wanna learn / understand
NQ would be an angle bisector right?
no , it need not be angle bisector
It's a implication of the angle bisector theorem ig
So in this case NQ is a angle bisector only if NL : NM = 1
ok thank you
i put angle bisector but i wasnt 100 percent sure lol
how do i solve this?
option D is 90
yea
is it 5x+x=90?
ohhh okay
thank you
Correct ans is B
For second one
I dont find any corresponding angles in the 1st question though... there arent even any || lines
ohhh
wait how
Corresponding angles need parallel lines right?
no i dont think so
wait they might
Corresponding angles are the angles which are formed in matching corners or corresponding corners with the transversal when two parallel lines are intersected by any other line
yea
what do i put for this tehn
but angle 3 and angle 7 hold the same position meaning they are corresponding
arcsin(0.960672361) returns 74, but it should instead return 106. if you subtract 74 from 180 you get 106, so is there something i don't know about?
am i supposed to subtract the returned angle from 180 ( or 2pi if im working in radians ) if the angle doesn't make sense?
find "k" (with solution please :'v)
arcsin only ever returns values between -90° and 90°
if you want the obtuse angle that has sine equal to your number, then yeah, subtract 180 - arcsin(...)
https://youtu.be/LOPT0mAsyCM there's this cool video I watched before regarding that
Learn more about the law of sine and cosine on Brilliant: https://brilliant.org/blackpenredpen/ (now with a 30-day free trial)
I came up with this tricky test question challenge for my precalculus students. Start with an obtuse triangle, give students the length of all three sides and one of the acute angles. Ask the students to find the measu...
okay so i have to evulate everything and decide whether the angle it gave me is the angle i need, or whether i need to subtract 180, etc
that's a pain
i'll give that a watch on my lunch break! thanks
i see the word calculus and i shiver
What is (tan 45° -1)
I was excited about this problem then I got extremely disappointed
what does the ... mean?
||k is 0 obv||
because tan45° -1 = 0
!nosols
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.
To fully express, k=(tan 5°-1)(tan 15°-1)(tan 25°-1)(tan 35°-1)(tan 45°-1)(tan 55°-1)(tan 65°-1)(tan 75°-1)(tan 85°-1)
And that is why we use the abbreviation as ...
Because else my hand hurts to type this entirely
are those standard angles? bc why not (tan10-1) or is that also included
You assume that the questioner wrote like that believing the reader of this problem notices the pattern of the angles: 5, 15, 25, 35,... and so on until 75, 85
And no ofc we do not know what the heck tan 5° or 25° is for now
This is why we have to think
What is 0Ă sin 385° Ă sin 5/8° Ăe^(â(2ÏÂČ-1))
Whatever we multiply anything to 0, 0 is still 0
im not understanding step 3 and 4
if i get angle 60 from my calculations and subtract that from 180 to get a second angle that is 120
if i add 60 and 120 together, of course it's always going to equal 180?? im adding 60 + the difference between 60 and 180 so i don't see how it'll ever be more or less than 180?
unless by original angle it means the angle that i'm starting with and use in my formula?
@rugged wind ^ spam
this is probably about an ambiguous case right (I just read smth about it coz I forgot it already)? I think it means that the original angle and its supplementary angle cannot be in the triangle
does it have any figure u could share? im also confused with the wording
this is the article im looking at
https://www.softschools.com/math/calculus/the_ambiguous_case_of_the_law_of_sines/
just confused bc if i subtract angle 80 from 180 to get an angle 100
adding 80 + 100 obviously equals 180 so i don't get what they're tryna say
<@&268886789983436800> scamp didn't get purged
do u know the very first step to determine if there are two triangles possible to be formed, one triangle, or none at all?
no
since you're given an SSA case, we wouldnt know for sure if the figure in the article has side b's length, long enough to enclose the triangle or at the shortest length to do the same
for that, we know that sinC/c has to be proportional with sinB/c as the law of sine states. Now, plug the given values and solve for the value of sin B
the value cannot be greater than one (or less than negative one), personally i dont know exactly why rn, but I'd say because 1 indicates sin90 degrees, and any sin of a degree higher (i.e an obtuse angle of a triangle) could be subtracted to 180 deg giving value less than 1
if the value meets this condition, say that the triangle can have 2 possible angles for the 2nd triangle, then the original angle or the given angle, 33deg, added to the possible angles of B (65.19 deg or 114.81 deg), should still give space to the 3rd angle u could easily find by 180deg= 33deg - (65.19deg or 114.81 deg) - angle A
do u get this elaboration @pseudo viper ?
because if the angle is greater than 180, then u basically have a triangle whose two angles are supplementary, and by property of triangle, it's simply false.
imagine a triangle with angles 120,60, and B. Doesn't make any sense right?
however if the second angle had a value when added to the given angle would give 90deg to the third one, then you have a right triangle as the only possible triangle to be formed.
i'd appreaciate anyone's correction on my elaboration
so im guessing by original angle they mean the first angle that we know?
bc that's what im getting confused with
yeah i think so
it's the only way I could say the steps are reasonable, otherwise im also confused by it
https://mathbitsnotebook.com/Geometry/TrigApps/TAUsingLawSines.html u can refer to this aswell
so lets say you end up with two angles
is there a way to actually figure out if one is the correct one
or do you just have to pick one based off what makes the most sense?
ig they're both correct
both triangles formed are correct, again there are two possible triangles, so, u have 2 possible answers
precisely
wouldn't one angle result in one of the lengths being shorter / longer
like if i get 60 and 120 as my angles
the sides with angle 60 would be shorter than the sides with angle 120
so wouldn't that allow you to figure out which is the one you actually wanna find
math is complicated smh
let's say it's angle B that can have 2 possible angles (acute and obtuse), it already has a given side, 10, and the only side length that could have two possible values would be the opposite side to A, since angle A could also have two values
to check if 10 as b' s length is correct according to law of sine:
sin33/6 = sin65.19/10 = sin114.81/10
~0.091 = ~0.091 = ~0.091
(sine of 114.81 is equal the sine of its complementary angle, if you're familiar with reference angle stuff)
also, in the figure, it's side a's length that shortens as angle B becomes obtuse, and vice versa
so to check if your angle matches up with what you already know, use law of sine as if you were trying to figure out side b ( if you just calculated angle B from the law of sine )
considering that u already determined that whatever angle you're checking is valid, then yeah
your welcome!
i've come to the conclusion that i hate the law of sine when tryna find an angle
it's a bunch of hassle đ
okay well that doesn't workl
(5 * sin(74 degrees) ) / sin(36 degrees)
(5 * sin(106 degrees) ) / sin(36 degrees)
both equal 8.17698038688
which i realise why now
so what do you do if you get an ambiguous case and need to know exactly which angle it is đ
hii
hello i know this sounds cursed but for my finals they made me find the equation of an inscribed circle
looking at the test answers now, i somehow got it correct, although that subject was a pain
maybe even a big one
i mean all the stuff related to finding equations of tangents from point outside of circle was excruciating
i felt like the universe was fileting my self esteem
,help
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!
,list
Use ,ls to obtain a briefer listing, and use ,help <cmd>to view detailed help for a particular command, or ,help to view general help.
If you still have questions, talk to our friendly support team here.
Render LaTeX code and configure rendering options.
â â â â â â â â â â tex: Render LaTeX code.
â â â â â â â â â ctan: Searches the ctan
â â â â â â â texdoc: Searches the texdoc
â â â â â â autotex: Toggle whether your LaTeX is automatically rendered.
â â â â â preamble: View or modify your LaTeX preamble.
â â â â texconfig: View or modify your personal LaTeX rendering options.
guildpreamble: View or modify the guild's default LaTeX preamble
Guild administration
â â â â â â â â config: View and set the guild configuration.
â â â â â â â â rmrole: Deletes the provided role
â â â â â â â disable: Disable commands in this guild.
â â â â â â editrole: Create or edit a server role.
â â â â â autoclean: Automatic deletion of messages in the current channel.
forgetrolesfor: Forget stored persistent roles for one or all members.
wowie zowie
Does anyone recommend a book for me to start studying geometry for the Olympics?
what do you do if you get an ambiguous case with the law of sine when trying to solve for an angle?
i know you can use the law of cosine to find an angle, but if i only have two sides and an opposite angle, then i can't use law of cosine bc i'm missing a side
i know in a real world scenario, you'll most likely know all the sides of the triangle
but what if you didn't?
This reflects the fact that SSA triangles generally do have two solutions -- one where the angle at the end of the first side is acute and one where it's obtuse.
Sometimes you can eliminate the "obtuse" case because it would lead to those two angles alone to total more than 180°.
But in the rest of the cases the ambiguity is real and you'll have to hope the problem contains other information that will tell you which of the solutions is the one you want.
How strong does my trigonometry need to be, in order to advance to calculus?
apparently you need a very strong understanding of algebra bc that's where everyone falls over
after almost 3 hours of trying to find this only using geometry, I gave up and used law of sines lmao. Was able to find it, fortunately (took some bruteforce coz im dumb)
@pseudo viper wanna give it a try?
there are a few ways the problem can be tackled, im gonna share mine in a few mins
i'm like 7 years outta school so anything i learnt back then is forgetten
i did run through the geometry section on khan academay lmao but i quite literally just ran to get some basics down
i see
well i'd say that it's doable with basic knowledge on circles, rectangles, and law of sine
at least on the solution I came up with
hmmmm
How did you use law of sines here?
It's not a 30 60 90 triangle
i'll share my solution later
im trying to make it understandable rn, coz the draft i have involves too much process that wasnt necessary after using law of sine
ooh, welp u could def give it a try and check
Ok I will
law of sines isn't only for a 30 60 90 triangle
I know
But I want to approach this problem more geometrically first
Without using the law of sines
gotcha
yeah i wouldn't know where to start
p much my only knowledge atm is algebra and trig
should probably spend a lil time on actual geometry
Welp idk how to do it with geometry đž
At least not yet
The answer I got is 4sqrt(3)-4Ï/3
@smoky jetty is that the answer?
hmm nope
if it's equal to ~ 1.87, it's quite close
ffs i used ballpen and im struggling to make my solution pretty now
@smoky jetty I'll be grateful If you find the mistake (if there is any)
ight im gonna share it
sorry if many parts are simplified to such extents ( i dont have correction tape with me atm, so mistakes were hard to erase, hence dirtier work), so feel free to ask for elaboration
@snow crystal
was this your final answer?
welp it's pretty off i'd say
But are you able to find any mistake in my solution
im checking rn
Cause I've been trying to for past 10-15 minuts and haven't found anything yet
but both of our handwriting looks so uhh lmao
Lol true
Did u find something?
sorry for the late response, i couldnt find exactly where u got it wrong
hopefully others could try and check
no, the correct answer is ~1.252
yeah, the video reference to it has the answer as 1.252 as well
That's weird
https://www.youtube.com/watch?v=2Seb863FnfU lol ignore the clickbaity title
This is harder than it looks!
Many people found a possibly easier way too! Here's a video I made about that method: https://youtu.be/_2lzv41RksA
Subscribe: https://www.youtube.com/user/MindYourDecisions?sub_confirmation=1
Playlist to watch all videos on MindYourDecisions: https://www.youtube.com/playlist?list=UUHnj59g7jezwTy5GeL8EA_g
This is...
had others try it as well (they were pretty much olympiad nerds) and got the same anwer.. lmao they said it wasnt even difficult
Ok so tell me what I did wrong
soorry but i just couldnt see the wrong part, and the handwriting also is pretty confusing to me
though certainly something is wrong there
Ok Im gonna show this exercise to my teacher and maybe she'll tell me
Though I'll have to wait for like a week or something



