#geometry-and-trigonometry
1 messages · Page 93 of 1
how much linalg do you know
would you be able to find the eigenvalues and eigenvectors of a matrix if asked
no
i changed subjects and stoped tensors at grade 7
started tesnor at last 3 months of grade 6
ok then maybe tensors are not yet in the cards for you
maybe learn linear algebra properly if you are so inclined
ok
@lethal zephyr continued from closed question #help-28 message
,tikz
\pgfmathsetmacro\myR{sqrt(0.5)}
\draw (0,0) circle (1);
\draw (1,0) circle (\myR);
\foreach \t in {90,180,270} {
\draw[dashed, gray] (\t:1) circle (\myR);
}
\path[pattern color=red!60, pattern=north east lines] (0.75,{-sqrt(7)/4}) arc ({-atan(sqrt(7)/3)}:{atan(sqrt(7)/3)}:1) -- cycle;
\path[pattern color=blue!60, pattern=north west lines] (0.75,{sqrt(7)/4}) arc ({180-atan(sqrt(7))}:{180+atan(sqrt(7))}:{sqrt(0.5)}) -- cycle;
vin100
those shaded areas can now be calculated (in terns of one unknown)
the rest is just algebra
Doing school project on end-users insights sort of like an interview where. https://docs.google.com/forms/d/e/1FAIpQLScGqyZVUqd6ohqK1bVYawpHwb1nddQU9krMmMakseYh6PyekA/viewform?usp=header
@uneven scarab for your question in #help-49 message, you have to show your work
you can start with letting some quantity with a variable, then use it to find it's relation between other quantities
\begin{tikzpicture}
\foreach[count=\j from 0] \i in {1,...,6}{
\tkzDefPoint(\j*60:3){A_\i}
\tkzDrawPoint(A_\i)
}
\tkzDrawPolygon(A_1,A_...,A_6)
\tkzDrawSegments[blue, dim={\(s\), 20pt,}](A_1,A_6 A_6,A_5 A_5,A_4 A_4,A_3 A_3,A_2 A_2,A_1)
% mid point of base
\tkzDefMidPoint(A_5,A_6) \tkzGetPoint{M}
\tkzDrawPoint(M)
% draw triangle
\tkzDrawPolygon[thick, blue](A_2,A_3,M)
% draw given circle
\tkzDefCircle[circum](A_2,A_3,M) \tkzGetPoint{O}
\tkzDrawPoint(O)
\tkzDrawCircle[radius, purple, thick](O,M)
\tkzDrawSegments[red, dim={\(R\), 10pt,}](A_2,O O,M O,A_3)
\tkzLabelPoints(A_1,A_...,A_6,M,O)
\end{tikzpicture}
vin100
@obsidian harness i think you can actually "do cogeom" while "pretending to do geom"
by drawing auxiliary vertical and horizontal lines
can we tell xy=0 the coordinate axes?
Can someone help me understand it please I think I got them all wrong and I am using this as my “rule” sheet
you want to find the area ?
finding similiar triangles i suppose
I think yea
do u have to prove congruency here?
Yes by either AA SSS SAS
Do you need to prove or just find the similiar triangle?
Prove
watch first five minutes if you're new to congruency in triangles:https://youtu.be/VXlFEilh-cw?si=NGiXUEEg3qGM6d7g
This geometry video tutorial provides a basic introduction into triangle similarity. it explains how to use two column proofs in order to prove if two triangles are similar using the mostly the AA postulates. Other triangle similarity postulates mentioned are the AAA, SSS, and SAS postulates. Theorems used in this video include the base angle...
Hi, absolute beginner here, could someone explain this to me pleasee.
what doubt do you have about this?
I don't understand why the fractions consist of the values they have, like why AE/AC = DE/BC
it is based on similarity of triangles
Since triangle ACB is similar to triangle AED we have that ratio
I see, so a fraction with two corresponding sides as the numerator and denominator is equal to an other fraction with different corresponding sides?
when two triangles are similar like triangle PQR is similar to triangle EDF we have the above ratio
yes the ratio of the corresponding sides of the similar triangle are equal
understood! thanks a ton!
one more thing, is there perhaps a name for this concept so I can refer to online resources?
similarity and congruency of triangles
an angle where you care about if it's clockwise or counterclockwise?
@echo sigil are you stuck on a specific question here
show your work
I can’t understand why BHS = PHS + BHP
that's directed angle
it's like
,tikz
\draw[->, blue] (0,0) -- (-5, 0) node [midway, below] {$\vec{a}$};
\draw[->, red] (-5, 0.5) -- (3, 0.5) node [midway, above] {$\vec{b}$};
\draw[->, thick, green!50!black] (0,0) -- (3, 0) node [midway, below] {$\vec{a} + \vec{b}$};
vin100
∡BHS = ∡(B̅H̅, H̅S̅) = ∡(B̅H̅, P̅H̅) + ∡(P̅H̅, H̅S̅)
= ∡BHP + ∡PHS
just like
,,\overrightarrow{AC} = \overrightarrow{AB} + \overrightarrow{BC}
vin100
the "element" surrounding the '+' is the same
So as I understand BHS = PHS + BHP since BHP has a different direction than other two so basically it is BHS = PHS -BHP?
try linking up what you've said with my vector analogy above
left (blue) vector has a different "sense" than the other two vectors, but
green (thick) vector is still the vector sum of the other two vectors
https://math.stackexchange.com/q/339142/290189
So,denote PHS =AC vector since it is the greatest angle ,BHS = AB ,BHP =BC,hence,AB=AC + BC ,however since BC has opposite direction it becomes AB=AC-BC which is correct
Note that a good notation is to have two same "element" around the letter '+'
Your choice of notation isn't goid
good*
hindering you to see the truth
Like AC + CB?
help me (number 4, not I've already solved it)
can someone tell me if its a nice qn
Prove or disprove
Given that r satisfies
Pr - pi r^2 = A
and we have a convex polygon of perimeter P and area A, we can inscribe a circle of radius atleast r.
What is radio length?
my friend said power of points can be used to solve it, which is pretty neat
Try mods
evett :DDDD
why can’t i turn the two negs into pos ?
because 1 - (-24/25)^2 actually means 1 - (-24/25) (-24/25) so there are actually three negatives
ok that makes sense
Hi or-ee-too.
Yall im failing geom i just got a 67 out 200 on my quarter test. Im so screwed pls i rly need someone to tutor or help me broo
what was your test on?
like specifically
It was on like sine cosin basic geom stuff, similarity figures and special right triangles
It was 134 out of 200
My teacher graded it wrong 😭💀
But now we are learning circumference, area of circles, sectors, test in a few days and i have no idea how to do it
might be hard to find a dedicated tutor, but you're free to post questions you're struggling with
ideally in a personal channel #❓how-to-get-help
$$cosA-sinA=\sqrt[2]{2}*cos(A+pi/4)$$.How can you get this result using sin A-sinB ?
wolly5114
ok just to fix your LaTeX
$\cos(A) - \sin(A) = \sqrt{2} \cdot \cos \left( A + \frac{\pi}{4} \right)$
Ann
but anyway, $\cos(A) = \sin\paren{\frac{\pi}{2} - A}$.
Ann
that isn't always true
its only true for x in [-pi/2, pi/2]
because that's how the inverse is defined
ahh, okay
@dark sparrow but how does $$\frac{\sqrt[2]{2}}{2}*cos(\frac{x}{2})-\frac{\sqrt[2]{2}}{2}sin(\frac{x}{2}$$ = $$cos((\frac{x}{2})+pi/4))$$
badtex
you should not put the equals sign outside of dollars
also your equality is incorrect anyway
also is there a reason why you insist on explicitly writing $\sqrt[2]{2}$ instead of $\sqrt{2}$?
ok your tex is still bad in many ways but now at least your equality is correct
and it follows from the angle sum formula for cos(x+y).
$$\frac{\sqrt{2}}{2} \cos \left(\frac{x}{2}\right) - \frac{\sqrt{2}}{2} \sin \left(\frac{x}{2}\right) = \cos \left(\frac{x}{2} + \frac{\pi}{4}\right)$$
Ann
this is what you meant to write, yes?
where does cos(x+y) come from in my equation?
yes
cos(x/2 + pi/4)
apply cos(x+y) = cos(x)cos(y) - sin(x)sin(y) with x/2 for your x and pi/4 for your y
you can't use the terms from the left to prove the right cos angle?
I've used ChatGPT but it doesn't explain how all that left equals the right side
!nogpt
Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).
not sure what you mean by this
are you asking like... is it possible to somehow go specifically from the left to the right somehow, rather than the reverse?
ok hold on
maybe we are getting off track somehow.
can we reset all the way to your original problem?
what do you really want to prove, and by what means?
wolly5114
this is wrong as written.
$\cos \left(\frac{x}{2} + \frac{\pi}{4}\right)$ Do you just expand this cos expression? That's what I'm asking How did that cos appeared from
wolly5114
ugh.
ok
wait
please
can you send the ORIGINAL problem EXACTLY as you encountered it. PLEASE.
im not going to ask for this a second time.
so your original question is $\lim_{x \to \pi/4} \frac{\cos(x/2) - \sin(x/2)}{4x^2 - \pi^2}$
Ann
yes?
well it was a difference of sines and ChatGPT showed me that answer
ok sorry i have to go now i cannot continue this.
can someone help me too
!da2a
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/
there is a mistake its "x to pi/2"
Prove that sin^2 a + cos^2 a = 1.
Pythagorean theorem: o^2 +a^2 = h^2
Divide both sides by h^2 and apply sohcahtoa
120 degree?
draw it out on the unit circle
and that's actually incorrect; the corresponding principal angle will be 180 - 120 = 60 deg
,w sin(120 deg)
is he asking for radian?
equation is false regardless
yeah in the off chance it was suspiciously close to -1/2
Wait i mean cos
,w sin(120 deg)
what are you allowed to use?
hello , i'm here cuz i have a math problem that i don't really know how to resolve. her's the question:
on a board made of 9 by 2 squares , we put coins on the square such that all squares either have a coin on them or share a side with square that has a coin on it. what is the minimum number of coins needed?
so i have an idea of the solution, which is five
but i just don't really know if that's the best solution , and i wanna know if it's possible to prove that this is the best solution
i thought of using some kind of graph but i also don't know how to use them
so if anybody got any idea on how to prove this is the best configuration of coins or on how to start , i would gladly appreciate it;
Did i post on the wrong channel?
probably not, i agree with you that it looks correct but i don't know how to prove it either lol
My teacher has the correction, i'll ask her for it tomorrow
what’s the source of this question
how does that have to do with a calendar
but yes 5 is the minimum
there are multiple ways of seeing this just think about it for a minute
The source of this question is a french math calender for 2023
How do i prove it though?
any ideas?
Well that's the thing, i don't have ideas.
I thought about a graph where the vertex would be the suares and the edges woukd link which square share a side with which, but that doesn't give me any ideas on how to continue
I definitely don’t think u need a graph (there could be a solution involving that), I am not very well versed with graphs
did your teacher say u needed a solution involving a graph?
I didn't ask her yet, i can ask her tomorrow. Do you have an idea?
why did u think to use a graph
Cuz that's what i'm currently learning in my free time and thought that it could work
so what would that be showing
That the solution found is the most optimal?
yeah
I mean to start off your solution does work
can u use just 1 coin?
do u know the equation for a circle?
!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.
what just happened to that guy
I went to sleep
X^2+y^2 =r^2?
I was talking to someone else, I think they deleted their messages
Oh okay
Oh, i have an idea
yes?
For a proof, it could be something about counting the number of squares between coins, and since to maximize the effect of one coin, you need to have no overlap. So you have to have 2 spaces between coins
(At least horizobtally, vertically is smth else)
Wait no
That doesn't work
Wait ik
I can show that to minimize the number of coins, k need the maximize the effect of a coin so that a square only shares one side with a coined square.
Then i can start at the extremities and show that the best way to put another coin is to put it the way the drawing show
Since there really is two solution with no overlap(the drawing and the drawing ritated 180 drawings. But both have 5 coins)
I can have 6 cases.
The cases are:
the coin is on a upper extremity ,
the coin is on a lower extremity.
The coin is an uneven number of square from the side of the board and is on a upper square.
The coin is an uneven number of square from the side of the board and is on a upper square.
The coin is an even number of square from the side of the board and is on a upper square.
The coin is an even number of square from the side of the board and is on a upper square.
Me trying to think but i'm using this as notes. Sorry, i'll write this somewhere else
oh
this is way too complicated
Then what's your idea? Personnaly i have no other ones
how many squares can each coin cover
Well on the current board, 3 if on an extremity and 4 on the rest?
yeah
I'm sorry but i don't understand
think about it
I already did. And i do not understand how this helps
what other information do u know about the number of squares
There are 18 of them
Oh
Yeah i understand
The ony way to divide 18 into addition of 4 and 3 is 3×4+2×3
And 3+2 = 5
Well technically there's 3× 6 but the number of coins is bigger so the answer is the previous one
given a unit circle, consider a convex polygon which contains the unit circle, given the area of the polygon is A, what is the maximum perimeter of said polygon?
I am the one who's gonna be the next ramanujan you know
trangle😻😻😻📐📐📐📐📐
fr
Geometry>calculus
Great @empty yew ! I think I'l have a good competition
Bro no one have same idea w me?
noone likes geometry
i like geometry
it's my first math love
doesn't mean I'm good at it tho
u can see calculus in the lens of geometry
so saying geometry > calculus is …
shows a narrow view of both subjects . i just have to say something u can safely ignore this part
I like geometry
I like it
||coordinate geometry||
Just a lot of content
do you know any angles of triangle ABC
yeah so which angle does that give you
Product of gradients of l1 and l2 will be -1
If they are perpendicular
Using the point intercept for of the gradient find k
you're overcomplicating it
Make the equations of lines and equate them for the intersection point
Well have you done the solution can you show ?
hi is this the channel for asking questions?
so if they're perpendicular
which angle would be 90 degrees
yeah lines L1 and L2 are perpendicular
do you have a diagram?
i can make a diagram if that would help
Please I
hm, this is not quite right
does this make sense?
uh i don't know what you mean by y coordinate of a line
let's go back to trying to find the angles of triangle ABC
You can’t
we're given that L1 and L2 are perpendicular, so which angle is 90 degrees
yes
and what else are we given about triangle ABC
Only one angle is given
Wait then the other two angles would be 45 each .
yes
part (b) just asks for the slope of L1
so if L1 forms a 45 degree angle with a vertical line
what is its slope?
You need the angle with the horizontal line I guess 🙂
Slope of any line is tan ( a) where a is smallest angle the line makes with the horizontal
But in our case it’s 45 🙌
No
AC perpendicular to BC
But this can’t be true as gradient is less than zero ( given )
But this can’t be true as the gradient for AC is less than zero but with this it is one
Try to use distance formula on both the sides of triangle
no don't use distance formula
if you have a vertical line
and another line at a 45 degree angle
what is the slope of the red line
💗geo
geometry dash 
blue angle a is equal to 43 degrees due to opposite angles, which means purple angle B is equal to 90 - 43, which means the bottom left angle is equal to 90 - (90 - 43) = 43
yes as shown by cloud i was able to make sense of that
well i don't really have to do the proof of it
its part of physics problems
and u just use it
xd
but proving it is pretty trivial too ngl
Im talking about another geometry unit
It’s where they give you a statement, which is the angle size and stuff like that and you have to find the proof which either given or bisector or reflexive property
Sometimes they let you find the statement, but they give you the proof
If you know what I’m talking about
For example: if AD = AD that’s the statement and the reason of it is reflexive property
hello
this one
it doesnt have to be trig function
just whatever u think is easiest
it touches 16,0 and 20,3
Or it’s a very restricted
can u create a function with this information
Trig function
yea thats how i went about it
any
That’s what your assignment is to do here?
that touches those two and looks similar to that
yes the test will be like this
we have to model stuff
and show how we did it and why we did it
then translate/transform it bla bla bla units to the right
or reflect it
and they say theres many possible answers so the thing they looking for is what our thinking and assumptions was
Well it looks like an inflection point, so it would likely have to be a trig function that is being multiplied by like 6 or something if 3 is the half way
dang bruh
😭
i thought of it as a parabola
and just used 16,0 as a vertex
then used a domain to restrict it a bunch
plugged in 20,3 to solve for the complete equation
that is one correct answer
I mean I guess it could be, it’s just not really a lot of information haha, you can make many functions look the exact same if you restrict its domain
yes thats the whole point of the test lmao
for us to show that we can use any function
because they just threw like 6 at us in like 3 weeks
Very odd test
yeah its lowk weird
and then for like higher mark we have to generalise the equation
like put in values like m and n which make the function move up/down left/right
well atleast after this ill learn something ive never learnt but only heard of before
calculusss
after this i mean lol
after the whole unit
of this
we will learn it next term/semester whatever u call it
ok
o ok
😭
yea ion think its possible with a trig function
my teacher used a cubic
everyone in my class just did parabola or cubic tbh
Yeah I’d just stick to simpler ones parabola is good, maybe try hyperbola or something
x^2 - y^2
oh
i never heard of one
ig imma learn that one too
well i heard of it once somewhere but idk what it is
Yeah good luck man that’s a rly weird assignment I’ve never done anything like that, sounds confusing especially at your math level
Like if I were you I’d be so confused lol
I had it easy and I was confused
You too !
Oh yeah one last thing
Don’t ask it for the answers I never advise doing so
But the AI chat bots are pretty decent at explaining complicated topics very simply
Again, seriously don’t have it do your work, but great tutor
gotta exercise GREAT caution even then.
ok tyty
Guys pls help me part c) of this problem
This is an illustration of this problem.
You can easily solve part a)
by using simple circle theorems
oops ill try and do part c
I did part a and b
Im trying to solve it
yeah, i can have a look at part c in a bit
but on the surface, at first i was thinking of pascals theorem?
but thats only a guess
ill get pen and paper and try it later
I dont think so
yeah i couldnt think of a use of that either
Can you see F is orthocenter of APQ ?
If i can prove it , i will solve this part
but it does look like it tho
AI and PT
how do you know PT is an altitude tho
AI is perpendicular to PQ
but how about PT?
Wait
Oh wait
triangle PTQ is an enclosed trianlge in a semicircle
so angle PTQ has to be 90
PTQ is an inscribed angle that intercepts a semicircle (O) so PTQ = 90', can you see that PQ is the diameter of circle (O)?
yeah then we make sense
yeah then it shows the altitudes, orthocenter so triangle PAQ is in fact a triangle so PTA are on a straight line
blah blah blah
why?
This does not prove that PT is the height of triangle APQ.
@restive flare
yeah im working on it
It is harder than what we were talking about
my eyes are tired from looking at the diagram 😭
Draw it by yourself , it may be easier
This is just a normal level in my highschool
im in year 10
Im in year 9
omg how are you guys doing so much 😭
Ill ask my friends tommorow to solve it
Because we are asian
What is your country ?
Malaysia
VietNam
But I go to a private school so ig its different
ooh nice
No , we study in a public school
wow
This is normal level
For some good student in my school , this problem is ass
wow im from a private school and we're still doing algebra 😅
Did you learn about AM-GM ?
arithmetic to geometric mean
What part are you doing in algebra ?
Damm bro , i absolutely give up rn , bye bro 🫡
have fun
I have a trig test on Friday
and I think I’m gonna fail
💔
(I’m a fool for taking AP precalc)
My main problem is applications, graphing, and memorizing the unit circle.
WAAHHHH YOU GOT IT 💪💪
TYYY 😭😭😭
YWWWW!!! 😭😭 i can link a vid to help memorize the unit circle
TY PLS SEND
HELP MY BAD
Microsoft teams go crazy
► My Precalculus course: https://www.kristakingmath.com/precalculus-course
Learn how to build the unit circle, including its coordinates, the angles in radians, and the angles in degrees. Then see how to use the unit circle to simplify trigonometric expressions, including positive and negative angles.
● ● ● GET EXTRA HELP ● ● ●
...
HAHAHAHHAHAHAH 😭😭
in trig we just did unit circle quiz
FOR REALL
TYSMMM
YWWWWW!!! 🤍 🤍
It has helped me understand so much I am in calc 2 now, I used to struggle with intermediate algebra even. It has not led me astray in its explanations, I just feed the lecture material I am given and have it reexplain it in a way that I can understand.
Can someone explain how to solve "Beginning with the graph of f(x) = x2, what transformations are needed to form g(x) = –(x – 6)2 + 3?"
i already did part 1 & 2
someone helped me with part 3 in a different server and i did that but i’d like it to be checked just in case
is f(x) = x^2 or f(x) = 2x?
Im having problems with polygon formulas can any1 help me
X^2
ok
what parts are u having trouble w/
I wasn’t understanding what they meant by the question but I get it now
Thanks though
hello
i'm having a bit of a trouble with factoring and completing the square method
can some one pls help me
Did you try a Taylor series expansion?
This algebra 2 video tutorial shows you how to complete the square to solve quadratic equations. This is for high school students taking algebra and university students taking college algebra.
Algebra Final Exam Review: https://www.youtube.com/watch?v=U0Y8nSmEpNM
Quadratic Equations - Free Formula Sheet:
https://www.video-tutor.net/...
try watching org chem tutor
you didn't say which level you were so this has some harder examples
also try Khan Academy for practice
you also wasted a lot of time by not posting a specific question that you're having trouble with
no clue what that is, turned it in already
ignore that
mentioning taylor series in a hs level geometry channel 😭
doesn't even seem to help or remotely be relevant to the problem 💀
yeah exactly
can i pay someone to help me right now PLEASE PLEASE
isnt there a help channel?
I saw this one r/math
u/lucasvb claimed that you can extend to 3d trig functions, especially with steradians
but i have a feeling sine and cosine are sort of dimension-independent, so are functions like trig3d_x(ω,Ω) not quite right?
the user's comment was the highest, but idk if it's correct
one way to extend to a 3d trig function is through mapping the x as independent real, z as independent imaginary, and y as absolute value of the equation
it turns the function to sqrt(sin(x)cosh(z)²+cos(x)sinh(z)²)
also the 3d parametric (sin(t),cos(t),t)
help
sum of angles on a straight line is... ?
yep!
so what would the left hand side be then?
yep!
ok thanks
,calc 31 + 9 * 14 + 23
Result:
180
you can check yourself also, but yes
np!
no, CG isn't x.
you're told CH bisects arc DHG.
do you know what the word "bisect" means here?
oh ok thanks
can someone explain what's the difference between the sine rule and cosine rule? im having some difficulties understanding those
the sine is lenght of opp site side from the angle over the length of the hypotunuse
and the cosine is the lenght of the adjcent side to the given angle over the length of hypotunuse
sine is opposite/hyp and cos is adj/hyp
tan is opsitte / adj
thats sine and cosine
use SOH- CAH-TOA to rember
Sine Oppisite Hypotnuse
and etc
alrighty
get it
bro i got a trig test tmmmrw i just learned all this stuff now
im so cooked
i know those soh cah toa stuffs
it's just im having difficulties finding the edges or angles of those triangles where there's no right angle
they use some kind of Sine Rule and Cosine rules
like sine rules
a/Sin A= b/Sin B=c/Sin C
type stuffs
yeah so if you recall your geometry, specifically triangle congruence types
for SSS, SAS you use the cosine rule
for ASA, AAS you use the sine rule
also look into the ambiguous case of the sine rule
there will be two possible triangles, with angles x and 180 - x
for example
go on
no I'm done for now
is there an example problem you'd like me to look over?
my bad
lemme try to solve the one above first
ah good idea, so try solving for angle B and B'
,w arcsin(10 * sin(33 deg)/6)
i think so
yeah then a good exercise would be to figure out the third angle
and then hence use the cosine rule to find B'C
or BC
Can someone tell me why this equals 28ft^2, I got 32ft^2 by using the Surface Area formula to find it but it’s wrong somehow, is it 28ft^2 because it says that there is no lid?
It is an open box so the area of 1 side won't be counted
consider: the box has no lid.
that's why the area of the top face shouldn't be counted.
that's calculus, not geo/trig,
post under the appropriate channel topic or claim your own personal channel #❓how-to-get-help
i would also argue that 56 sq ft is also acceptable because the interior of the box could be considered the surface area too
5
yeah because each time it accelerates it ignores x^9 so that can cause the number to concept to the power
where in Norway
more like a geology question 
4.91300
why does he ping so weirdly
why not bro
do you not agree that norway is a big rock? 
😂
Hello everyone, my name is Alan and I'm from Brazil, I passed the math exam at Unesp here in the state of São Paulo and I need to study for a trigonometry test in about 4 days. What do you recommend?
For me to study for this
I started finishing the semester and I'm asking
I recommend studying trigonometry
But is there any platform to study trigonometry or some app, I don't know?
I don't know
Nah man homie changed name for answer is crazy
☠️
I can’t stop laughing this is crazy
Lmfaooooo
Why u both got same sentence lmfao


Khan academy
Is free
With no ads
I suggest that
What happened here 
U three back
What’s the hardest thing it geometry and how do I prepare for it next year
Read egmo book by evan chen
How should I study from Euclid's elements
It is way too complicated
Is there a similar book slightly easier to understand
there are plenty of proof-based high school geometry books which present most of the same content in a more digestible format
Any particular one which I can refer
idkk
but i heard of uhhh
wait lemme gg it
theres a series of books by j. e. thompson called "mathematics for self study", tho it covers multiple branches. you might wanna check it out.
hehe i always thought it'd be funny to read the elements for absolutely no reason and in spite of my ignorance
Help
So
Scale factor = 15/12
=5/4
1056pi • (5/4)^2 = 1650pi as your surface area.
For C-B
Volume: 4608pi • (5/4)^3 = 9000 pi
May be confusing since it’s a mix of 2 different concepts.
@uncut crest
K thx
I was told by my teacher to square for SA and cube for V but I didn’t know what to square and cube
!noans
The purpose of this server is to help you learn, not to hand out answers. Do not ask someone to give you the answer directly.
The purpose of this server is to help you learn, not to hand out answers. Do not ask someone to give you the answer directly.
@lapis moon
Oh alr
I’ll explain in depth next time
just use wolfram alpha
Instead of a complete solution, give the question asker hints/guide, so as to leave a room for them to solve their own question themselves
That would allow them to learn by doing instead of passive learning
<@&268886789983436800>
Ok
!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.
What so you guys think?
Amazing
Do you have any more of these for different concepts by any chance
Or where did you find these?
Made these
Yes but why?
Do u need by any chance?
I have got kepler and dual nature of light
My youtube channel
Three videos have been uploaded
The videos are just intriguing.
Can I find the area of a triangle knowing three sides, but no height
Yes
Look up Heron's formula
awww man I can't use that, this means I have an entirely different problem
You could always find the height yourself 
Find one angle using trig and then do trig area
Yeah just wondering how to do it
Put it in coordinate space and shoelace or draw a rectangle around the triangle
Use extended sine rule to find the circumradius and do A=abc/4R
etc
is this accurate or not
yes
GUYS can anyone please explain?
I think i can help: i think the answer is 135° and 225°
For the first one
This is how I solved it. First, i tried finding the reference angle. We are given that $$\cos \theta = -\frac{1}{\sqrt{2}}$$. The reference angle is the angle whose cosine is $$\frac{1}{\sqrt{2}}$$. This is a special triangle value, and the reference angle is $$45^\circ$$
Jesuslover123
Next, determine the quadrants.
Since $$\cos \theta$$ is negative, $$\theta$$ must lie in the second or third quadrants.
Jesuslover123
Thirdly, find the angles in the second and third quadrants.
In the second quadrant, the angle is $$180^\circ - 45^\circ = 135^\circ$$In the third quadrant, the angle is $$180^\circ + 45^\circ = 225^\circ$$
Jesuslover123
And lastly, consider the range 0⁰ to 360⁰.
The angles that satisfy the equation $$\cos \theta = -\frac{1}{\sqrt{2}}$$ in the range $$0^\circ$$ to $$360^\circ$$ are $$135^\circ$$ and $$225^\circ$$
Jesuslover123
Hope this helps!!! I tried my best
THANK YOU :))
Eh
you can use single dollars to have your LaTeX stuff be inline
compare: this is an inline formula $x^n+y^n=z^n$ while below is a displayed formula: $$e^x = \sum_{n=0}^{\infty} \frac{x^n}{n!}$$
Ann
Thanks, good to know.
No problem😁
Hints:
-
if cos x = 1/sqrt(2) then x = 45°
cos is negative in the 2nd and
3rd quadrant -
sin(210°) = sin(180°+30°)
cos(300°) = cos(360°-60°)
Hint:
Sum of angles in a triangle is 180°
@somber coyote
Here’s how I solved it
- Initially, My goal was to use inverse cosine. So,
$$ cos^{-1 } (-1/sqrt{2}) $$
The answer would be 135 degrees
Now you take 135 and subtract by 360, since you need cosine to be negative. X= -cosine
Answer would be 225
Immanuel-TP
This works because Inverse Cosine gives us our main output as the unknown angle since we know 2 sides of the triangle.
!noans
The purpose of this server is to help you learn, not to hand out answers. Do not ask someone to give you the answer directly.
I just explained it?
@lapis moon
OP doesn't give the numerical answer, that's why I put "no answer"
when explaining, give hints/guide, which is a global description of the detailed steps
and leave OP a chance to work them out
!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.
please let the question asker to do their HW honestly
instead of giving the answer directly
does anyone wanna do some trig? i wanna learn but it's hard to focus alone (ADHD)
how do you solve for the red area ive been trying to do this for a while but i cant crack it
Wow
hmmm
here's a youtuber and a former math phd student having adhd
https://youtu.be/-wf1M9oABX8?si=Dx4ECCwXpidEuoxy
I overcame my ADHD with THIS study method! How do Harvard and MIT students study? How to effectively memorize without forgetting? The most effective evidence-based memorization method. Why memorization is key for studying, even if you're a STEM student. How to use Anki?
▬ In this video ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬...
the area of the semicircle is 25 pi upon 2
Sooo
the red area is about half of the semi circle
i think it could be 25 pi upon 2 into 1 upon 2
Thats 25 pi upon 4
@spare nova
Thats a really cool quesiton tho
strange i got 9599683 / 655800
how did you get your answer?
Nevermind i was wrong
its 25*arcsin(1/4 root(14)) -100arcsin(sqrt(14)/8)+25/2 *sqrt(7)
its 25*arcsin(1/4 *root(14)) -100*arcsin(sqrt(14)/8)+25/2 *sqrt(7)
thanks i cant format for my life
Hello guys u clean wondering if anyone could help not sure which 2 i got wrong
why is the top and bottom measure different?
the bottom one should be 3.5sqrt(3)
unless the solid is not a prism
Hint:
Try to draw sectors in the full circle and quarter circle
I have a question everyone
is similarity of triangles an equivalence relation?
actually no im stupid thats not what i meant to ask
is it transitive?
do you think that it is or that it isn't
try to sit down, write out properly what it would mean for the similarity relation on triangles to be transitive, and attempt to prove it
alright gonna do it
Hello, i am stuck on a problem, and well, i don't even know where to start...
Here's the problem: we have a triangle ABC that is equilateral whose side is a (a strictly positive) . is the symmetric of C by the point symmetry of B. We draw the line (delta) which passes through P, M which is on [AB] and N which is on [AC] . We say that BM = x.
What is x for CN= 2a/3.
Here's a drawing of the problem:
And well.... i don't even know how to express the relation between x and CN so here i am
Does anybody have a way to start on this problem?
Pretty easy , js find the semi circles area and divide it by half
,rccw
Please rotate your picture, so that PC users can view it More easily
Sorry
Hint: ||use Menalaus' Theorem||
Seems like something new to learn, thank you
what exactly made you think it was half its quite clearly not
If create a circle outside with a radius 10 then the circle ( red area ) could be divided into four quadrants as by the area of the bigger circle
Pi r square
25 pi
oh im wrong!
In 2-dimensional geometry, a lens is a convex region bounded by two circular arcs joined to each other at their endpoints. In order for this shape to be convex, both arcs must bow outwards (convex-convex). This shape can be formed as the intersection of two circular disks. It can also be formed as the union of two circular segments (regions betw...
crazy formula: area of circle - lens = area in problem
yes, any triangle
thnx
has anyone came up with a geometric interpretation of say the derivative of surface area? I'm not talking about seeing things as rates of change
for a sphere that is
im just curious because since SA is V', then what does SA' mean?
and the reverse: what does ∫Vdr mean?
well $\odv Sr = 8\pi r$ which is four times the circumference of a great circle, i'm not aware of any further significance. a more natural connection is that the derivative of a circle's area with respect to the radius ends up being the circumference
cloud
the integral of the volume with respect to radius would be some sort of 4-dimensional hypervolume quantity
yeah, just not the actual hypervolume. aka $\frac{1}{3}\pi r^4 \not = \frac{1}{2}\pi^2r^4$
idk if there's really any analog for this quantity
wdym by great circle?
on the earth an example would be the equator
basically any circle which divides the sphere into two equal hemispheres
so it shares the same radius and center as the sphere itself
TooMuchofEverything
well you wouldn't necessarily expect that integrating the volume of a sphere to give the hypervolume of a hypersphere, just like how integrating the area of a circle doesn't give the volume of a sphere
yeah
hey...im new to discord ...wont mind having friends here 🙂
Do you guys think i'm good ?
One of the ways is to draw a line NK parallel to BC with K on AB.
How to find the principal solution from 0 to pi for tan(x)+sec^2(x)=1 ?
ping me if anyone know how to find this.
use trigonometric identities
I would suggest you use the relation tan²x + 1 = sec²x
tan(x)(1+tan(x))=0 then x=0 and sin(x)+cos(x)=0 what to do here?
for tan(x) = 0 there are more than 1 solutions
and also you don't need to convert to sin and cos for the 2nd
just simply 1+tan(x) = 0
so tan(x) = -1
how to get that multiple x here?
if tan(a) = 1, then what is a?
pi/4
yes
now cuz this is -1 instead of 1
and x ranges from 0 to pi
in which quadrant is tan negative?
second and fourth
tan(pi-pi/2)?
no
yes
@summer cradle isn't tan(x)=0 at two x's?
x=o,pi
then x=0,pi,3pi/4
is this correct?
yes that's what I am saying previously
^
yes
ok thank you so much @summer cradle
@summer cradle do you know about conditional trig and determinants?
determinants I think you mean in matrix?
and what's conditional trigonometry?
never heard of that term
maybe give an example
I may know it but only didn't knew the term
A+B+C=pi and some equation to prove using this condition
ohh yes I know
I want to solve this
I don't really remember the determinant formula for 3x3 matrix
np
Here is the formula
that's too tedious using formula I want to find the determinant using properties and conditional trig directly
$\sin^2 B \cot C - \sin^2 C \cot B - \sin^2 A \cot C + \sin^2 C \cot A + \sin^2 A \cot B - \sin^2 B \cot A$
south
https://www.doubtnut.com/qna/643224187
anyways found it
tedious no matter what you do
it turns out the coordinates here are real so they form a degenerate triangle, but there does exist a transformation to get from one to the other
hint: ||you need a reflection and a dilation||
(matrix is sideways but reorienting it is trivial)
this what you're looking for?
I can't understand what you're trying to say.
did you want a solution for this problem without manually computing the determinant?
or is your confusion about how to apply this idea
am i misunderstanding you?
according to skibidi of the tangent, the sin of 40 degrees is hawk tuah gyatt
https://www.desmos.com/calculator/3r1lfj2g9c
I got sucked into the volume formula for n-spheres. Knowing that the SA of a sphere is V' and the C of a circle is A', I wondered if there's a pattern. Since the SA of a 3-sphere is 4 circles, I wondered what's the pattern for all other n-spheres of that nature.
gyatt(pi/2) = 1/sqrt(skibidi)
impossible for the 5,5,10
not strictly impossible but it would be a degenerate triangle (overlapping line segments)
is gpt wrong here?
the number atthe end of the sinus equation or function i dont know im not english is +1 (vertical movement) so from what ive learned in the last 4 hours shouldnt the line start from 1 rather than 0?
pls someone help me its 4am i wanna learn this and go sleep 🙏
@cunning lion do you know?
if you want to plot a function and get an accurate plot i would recommend desmos
chatgpt doesn't inherently "know" what a function looks like so it just plotted y = 2sin(x) because it has the more classic "sine shape"
used this and apparently it starts in -1?
i haveno clue how this happens becuase apparently the +1 at the end i think that would mean it starts from 1 not 0 or -1
if you plug in x = 0 you get 2sin(0 - pi/2) + 1 = 2*sin(pi/2) + 1 = 2(-1) + 1 = -2 + 1 = -1
the +1 determines the midpoint line that the sin oscillates around
so the midpoint line is y = 1 in this case
whast the midpoint line im sorry i learned math terms in croatian
oh the average
OHHHHHHHHHHHHHHHHH
I GET IT
I LOVE U @cunning lion
❤️
so it does start in Y=1 but just x is moved 1 to the right im so stupid
hey does anyone know how you can get angles BAD and CAO are equal right off the bat for this problem?
got a diagram?
it's so easy
yes!
tell that too
do you know how to plot complex numbers on the complex plane?
yes
ok then so
i posted an answer already and all you said was "i dont get it"
can you be more specific about what you dont get
I can understand this
ok....?
I didn't understand the sentence you said there
this is really tiring, i dont know which sentence youre referring to, please be more specific
i'm not sure if this is the right place to ask but why are trig functions the way they are? i understand that sin(x)=o/h etc. but i don't understand why they are defined like that
didn't you ask the exact same question before?
this is my first message on this server
are you asking where their names come from?
or are you asking why we care about side ratios at all in the first place
deja vu
i guess what i'm asking is what actually is sin cos tan and where did they come from??? (i'm not that experienced in maths so i only know sohcahtoa and a bit of sin rule and cos rule)
sorry if im not being specific, idk exactly how to articulate what im asking
A) "Why are sine, cosine and tangent named this way? Who came up with those words?"
B) "So... why do these functions matter exactly? Why would we care about the ratio of some sides in a right triangle?"
is your quandary more like A or more like B
mostly A, a bit of B???
ok right
sorry i realise im being not very specific
no actually i have just the thing.
essentially, sine is kind of the result of a centuries-long game of broken telephone involving Sanskrit, Arabic and Latin
but at its roots the idea is that of a right triangle inscribed into a circle, and mirrored across one of its legs, so that the doubled opposite leg and the circle arc kind of form something that looks like a bow
the co in cosine stands for complement, in the sense of 90° - x
(so like, the identity cos(x) = sin(90°-x) is kind of what gives cosine its name)
fair fair
tangent is more directly from the latin word for "touching" (in fact we still use this word for a straight line that touches a circle)
it and secant are best understood in the context of the unit circle
thank you very much!
like this
secant means "cutting", and etymologically is related to words like section
if have the adjacent how do i find the opposite it is adjacent x tan (angle) or adjacent / tan (angle) or smth else
cuz i lowkey kinda forgot
nvm got it
what would this triangle look like
Given triangle ABC, we find the median AM and the distances BD and CE of the vertices B,C from AM to be
i mean where would you place points D and E?
extend AM and drop perpendiculars from B and C
their intersections with AM are D and E
when we say “distance from a point to a line” we mean the perpendicular distance
Can someone explain to me how to solve trigonometry i mean how to use the formulas of trigonometry