#geometry-and-trigonometry
1 messages · Page 364 of 1
no
i take a class on geometry'
in school
they offer that at my school
anyways
what do any of these mean\
think about it
what
if you live in abilene can you live in texas
so that one is true
im not good with making inferences about latin/greek roots
inverse is if you live in texas do you live in abliene
no
i mean you can live in austin
you dont have to live in abilene
abilene is one city
so if you live in texas you CAN live in abilene
"To form the converse of the conditional statement, interchange the hypothesis and the conclusion. The converse of "If it rains, then they cancel school" is "If they cancel school, then it rains." To form the inverse of the conditional statement, take the negation of both the hypothesis and the conclusion."
Given an if-then statement if p, then q, we can create three related statements: A conditional statement consists of two parts, a hypothesis in the if clause and a conclusion in the then clause.
👍
bye
Anyone know how to solve this?
The square of an angle measure is 15 degrees more than twice its complement. Find the measure of each angle.
what have you tried so far?
Do you still need help with this?
sin^-1 is the arcsin function, not 1/sin(x). Basically u input a value between -1 and 1 and it tells you what angle between -90 and 90 degrees gives you that sin value
Or, sin^-1(sin(x))=x
and sin(sin^-1(x))=x
.
aye
how can i find the cos(2pi) using unit circle?
based on the unit circle at angle pi the coordinates are (-1,0)
so i took the first coordinate which is cos, and multiplied by 2
but that's wrong so what do i do
hiya, can someone please help me find the equation for this cotangent function
that are degrees?
if that are degrees, then, the function is $\frac{1}{tan(x-90\textdegree)}+2$ or in radians $\frac{1}{tan(x-\frac{\pi}{2})}+2$
R0bin
since sin^2(x) + cos^2(x) = 1, what does sin(x)+cos(x) =?
also 1? because if u sqrt both sides its still 1
im trying to solve the inequality cos(t) + sin(t) > 0
so i've set it = 0 just to see when its = 0
and then solved to get sin(x)/cos(x) = -1 which is tan(x) = -1
hello guys I just wanted to know if we can check that cos(90+x)=-sin(x) quickly through some website?
What do you mean through website ? You want to prove the formula or whaT?
i just want to quickly know if the equation is true or not
Woho mate 😄 We will go over this but this is something you should never do 😄
Fastest intuition way to see if formulas like this one are true is to look at unit circle and if you want proof of it you use formula for cos(x+y) 🙂
this formula?
yes
alright thanks I was a little confused because theta and 90 were in the same bracket.
yeah… i figured that out hah
If point P is (0,5) on the terminal side of angle theta, how do i find the lengths of the legs to find the trigonometric functions?
Use algebra, replace the width with a variable and find out what the longer side is in relation to the width(hopefully I make sense)( @upper karma )
Also don’t forget there’s 4 sid3s to fence :)
Hello, there is a question.
If anyone can help me, please DM me.
It's of coordinate geometry.
just ask here
Let A, B be two Points on the plane such that A is different from B, then there is a unique line that goes by them
a plane i mean not the
Hey guys, so I know how rotational matricies work, however, I wasn;t too sure how to apply them to points, could anyone explain that process? It would be greatly appreciated.
make your point into a column vector x and then multiply R * x (where R is your rotation matrix)
this will apply the rotation encoded by R
@dark jacinth
how do you simplify this?
Hello?
IS this free?
I would need help
Anyone here? when is the best time to be here?
I think u should just put the prob up
Yup
to go from radians to degrees, you multiply by 180/pi
so just multiply the given angle (which is in radians) with 180/pi, and you'll get your answer
still here?
I'll be back tomorrow
help
hello, i can help you with this problem, please DM
they've misspelled nonagon
anyway, are you familiar with complex numbers? @compact oasis
Yes, i am familiar with them
consider the nonagon as being in the complex plane, oriented and scaled such that its vertices occupy the 9th roots of unity
and let A be the vertex sitting at 1
let u = e^(2pi/9 i) be the first vertex counterclockwise from 1
then you have $x = |u-1|, y = |u^2-1|$ and $z = |u^3 - 1|$
Ann
I am anot that confortable with complex numbers as of now, can you give me another approach?
Oh, alright i will try to learn more about complex numbers first today
I got a solution that involves not *much trig bashing
The trig could probably be averted completely with a few more Ptolemy’s
solved without advanced trig (does law of cosine counts idk)
consider triangle ABD with law of cosine:
z^2 = x^2 + y^2 - 2xy cos(ABD)
consider isosceles triangle BCD, since it's a nonagon, BCD = 140 degrees, and therefore CBD = 20 degrees
and making angle ABD = angle ABC - angle CBD = 140 - 20 = 120 degrees
therefore, z^2 = x^2 + y^2 - 2xy * (-1/2) = x^2 + y^2 + xy
Wow, thank you so much

😃
Does anyone know if $\frac\pi 2+2\pi\mathbb{Z}$ is a valid expression for saying: $\frac\pi 2+2k\pi$ where $k$ is every number in $\mathbb{Z}$?
NoRysq
I hope this fits here #category-theory was not the right place apparently
nvm solved
I need help anyone available ? good afternoon
hello hello
i’m taking trigonometry currently and i know how to do this problem but could someone explain why it’s necessary to use the 30-60-90 triangle rather than using the distance formula with the coordinates that lies in the quadrants? like (1,1)
I would just use the definition of cot and use the unit circle
pls help me here
Mmm tfw when you cant solve an 8grader problem 😭
There’s a given triangle ABC with <C 80, angle bisector CL crosses the perpendicular bisector of AB at point Q. What is <AQB?
This I believe
No im talking about me as a postgrad engineer I solved your question in one of the Q channels
<@&286206848099549185> bless you
Q should be outside the triangle lol
70=10c
c=7
70=6d-2
6d=72
d=12
@upper karma
idk im bad at math idfk if this is right lol
$\sin^2{x}+\cos^2{x}=1$
elon mass
this allows for some simplification on the top
sum1 pls help me
does y = 122
x = 65
does z = 57
sum1 pls help
immediatellylylyllylylyl
<@&286206848099549185>
ans coming same as yours
please <@&286206848099549185>
If your question has not been answered for a minimum of 15 minutes, you may use the Helpers tag once. Please do not try to bump your question using this ping unnecessarily. Do not abuse this ping. Do not individually ping users with the Helpers tag without their express permission.
@upper karma do you still need help with this?
have you made any progress?
yes i have
please share
i try to factor => doesnt work
i try to blur away the -1/2 thing but it end up to complicated for me
are you familiar with complex numbers at all
u gonna use the euler ?
yes
2cos(t) = e^(it) + e^(-it)
bruh
idk if i can turn this into pure trig
what does the e thing do ?
i knew it because of google , but nobody teaches me that
and i dont know what does the constant do ?
hold on what
hold on as in give me some time
ok
well shit i can't figure out how to do it without euler
so can u do the euler for me
and i will figure it out
my teacher throw that shit to me without teaching me the euler
well damn
what ?
i don't have anything else to say
the last three lines are just recognizing a GP and dividing out by things that are known not to be zero
Why does sine of theta specifically equal opposite/hypotenuse
for 3g I'm getting the opposite wrong
I don't know why. https://fog.ccsf.edu/~wjeh/math95/circle_approach/trig_answer_circle.pdf
<@&286206848099549185>
Can someone help me with geometry?
I need an A to get first seating in my highschool magnet, but I have an E right now.
That is how it's defined
Why though?
Long ago mathematics needed something to describe relations between sides and angles of a right triangle. Sine is just one of the 6 possible combinations to describe an angle in relation to the sides of a triangle
that's not the answer I'm looking for tbh, it had something to do with like chords and saying sine = half chord something
It does make sense if you know about the unit circle
3-4-5 triangle
cos = 0.6, sin = 0.8
and thats the coordinates
It is especially helpful when dealing with polar coordinates
What im asking is how they actually founded sine of theta
why did it mathematically make sense to say sin of theta = o/h
Like many mathmatics operations we just decided a name for it. All the trig functions represent is just ratios between sides.
i just dont understand math 🥲
what am I missing here? am i picturing it wrong?
Try using the law of sines
Also, I think you got one of the angles inccorrect
The one in the top right should be 5 degrees (I'm pretty sure) because 180-31 = 149, and 180-(149+26) = 5.
Can someone please help me on this Trigonometry problem?
cot t = -1.2345, sect < 0. Find t
enter the coordinates of the vertices of (Rx-axis ∘ r(180°,O))
what does equidistant mean?
which one do i do first/ enter the coordinates of the vertices of (Rx-axis ∘ r(180°,O))
are you asking where the name sine came from
cause it's a pretty long story
but the TL;DR of it is that it ultimately came from the Sanskrit word for bow string but it went through a bunch of broken telephone involving Arabic and Latin
no, clearly nobody on this server of thousands has even a millisecond of time to spare on this day in particular (/sarcasm)
Can u tell me some of the theorem that looks like the Pascal and the Newton ones ?
I'm just asking why does sine equal opposite/hypotenuse and it had to do with chords in a angle or something
I got my sources from this and other quora stuff: https://www.quora.com/What-does-sine-mean-and-how-do-you-prove-that-sine-is-equal-to-the-opposite-side-over-the-hypotenuse
sin(θ) = opp/hyp is the definition. there's nothing else to it.
ok...?
Which question?
k wait let me try
Okay
what have you tried so far?
I barely know this and he expected us to do it, we had a sub and I try another paper nope I don’t get it
do you know the slope formula?
Yes I know the formula
can you try applying it
Okat
also your answer for Q2 is wrong
yes just saw that
Oh
Yall know 5
Idk if this is in your course or if it works but I'd apply distance formula
This is what I did.
First step is distance formula, then you just apply the points given to the placements and solve
I mean I am an idiot 🤷
But that's how I'd do it
tell me the answer if u know
Does anyone know how to do this?
I never learned this but honestly I'd just try and graph it out
Maybe you tried that already
But that's all I can think of
I am a bad drawer so it just came out as a mess
I'd just draw the origin
Then draw x and y axis with a thick line
Then put in points for the x and y values
Use a ruler
Might help, might not
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wait wrong chat sorry
yes
k
do uk how to do it?
I am trying
ok
is any line given parallel or something
no
I dk if this the right ans but I can tell you how I did it
can u explain how u got it
yes
F+G=102 exterior angle property and angle 65 and angle opposite to it will also be equal to 102 so let the opposite angle be y so from equation 65+y=102 we will get y=37 and as F+G=102 and angle 65 + angle 37 =102 I put them in equal and compared the equation so f=65 and g=37
Did you understand it?
no💀
Is there a fast way to get the quadratic form of an ellipsoid given the rotation matrix, length of each of the three-axis, and the location of the ellipsoid's center in some world coordinate frame?
The straightforward approach seems to be applying the homogeneous transformation matrix (new_h = [R t; 0 0 0 1] * old_h) on some general point on the surface of the ellipsoid and then plug the resulting x, y, z (new_h = [x; y; z; 1]) coordinates into the general equation of an ellipsoid and expand that to get a quadratic form (writing x2/a2 + y2/b2 + z2/c2 = 1 in terms of the old_h, rotation matrix, and translation matrix parameters).
But is there a faster way because the calculations are tedious and I was hoping there is some generic quadratic equation of an ellipsoid but I can't seem to find it on the internet.
I have a problem: a circle is inscribed in an isocele trapezoid with bases equalling 40cm and 10cm. Find the area of the triangle created by the touching points of the circle and the trapezoid's sides, and the touching point with the smaller base.
i have no idea how to do it
sry didnt mean to be rude..
@sleek scarab how much have you solved until now?
this much
ignore the serbian lol
Alright
Now that you know h you know R(the radius of the circle) and that is h/2 = 10. After that draw to lines that are perpendicular to the AC and BD - those are radiuses. If you draw another radius perpendicular to CD (that would be OF) you will end up with two new shapes - CHOF and DGOF
I follow
These shapes both have the same angles - two are 90 degrees, one we will denote as x and it will be the angle formed at the lower base when AC or BD meet with CD, and the other will be 180 - x. Those are HOF and GOF. Then you will end up knowing the angle HOG, which is 360-2×(180-x), thus HOG is 2×x
We can easily find the value of cos(2×x), since we can use either of the right angled triangles on the left and right. We can use the formula cos(2×x) = cos^2(x) + sin^2(x). By using basic trigonometry we can determine that cos(x) = 3/5 and sin(x) = 4/5
We can then use this formula : HG^2 = OH^2 + OG^2 - 2×OH×OG×cos(2×x)
This leaves us with HG = 16
Then I used the formula 2×R = HG / sin of HEG. That is 20 = 16 / sin of HEG. That means the sin equals 4/5
I can then find out the value of that angle's cos with the formula 1 = sin^2 + cos^2, and that is -3/5 because the triangle is clearly obtuse, since the center of the circle is outside that triangle.
I can then find out what the values of HE and GE are by using the same formula I used to find HG. This leaves with HE=GE=4√5. We can then use this formula for the area: S = (HE×GE×sinHEG)/2
And then the final answer will be 32
Any questions?
Could someone help me? I’m suppose to find x and y and the red lines are parallel and the blue lines are parallel as well
as red lines are parallel so 3x=105(Alternate interior angle) and in the triangle in which two angles are 2y and x given the third angle in the triangle will be equal to 105(Alternate Interior angle) so u know already know the value of x from equation 3x=105 so apply angle sum property and you will get value of y also
Thanks
Hello, I was wondering why it became sin(60)? He said that 120 degrees is in quadrant 2, and it forms a reference angle of 60 degrees. He said that the reference angle is an angle between the hypotenuse of a triangle and the x-axis. He also said that 120 degrees isn’t in the 30-60-90 triangle. But afterwards, he formed that triangle here.
It’s because 180 minus the given angle isn’t it? Since it is in quadrant 2?
Yea, I think it used sin(180°-θ)=sinθ
Oh okay, thank you
Greetings fellow balkan dude
What am I doing wrong with transformed outputs? If I transform the key points on a cos(x) function I keep getting incorrect outputs.
Can anyone help with part iv?
?
what r the z1 values tho? do you have the polygon area?
would it be possible for someone to help explain how to do trigonometric inequality?
I'm not quite sure about which should be > or <
yo can someone help me understand why the equation of a plane parallel to the z-axis will be of the type ax+by+d=0? I think the distance from z will be the same for all points on such a plane but that’s as far as I got
It’s there…
I think it will be constant because the radius R and r are of same circle so there value will be equal no matter if the triangle increase or decrease so there ratio will always be equal to 1
Hello, kindly DM me for help
but show some work of yourself bruh...
??????? Do you not know how to sketch a simple Argand diagram lol
whats the answer here? thought it was y1-y0 / x1 - x0
()
()
this is equivalent to what?
the selected option
iisn't the selected optiion the negative version of slope?
$\frac{k}{k} = \frac{-k}{-k}$
ℝamonov
lol they're the same
i triied to disprove you wiith an example but it came out equal
thanks
Hello, is the reason why the inverse of tangent 1 is 45 degrees is because, the value, which is 1, is positive. So that’s in quadrant 1. And in 45 degrees, it is (√2/2, √2/2) and when you divide them both you’ll get 1?
that sure is a bunch of words you just said.
the 'reason' why arctan(1) = 45° is because tan(45°) = 1.
Reason:
A 45-degree right triangle is clearly also isosceles
Done
Oh okay 😅 I forgot, but how would I know that arctan(1) = 45 degrees? I understand that tan 45 degrees = 1, but how would I know if I was asked what the arctan(1) is? And I didn’t know it was 45 degrees? I have to look at the unit circle and find two coordinates on quadrant one that when I divide will give me 1?
arctan(1) is the angle whose tan is 1.
if you're looking at the unit circle there is a way better way to visualize tan than just 'dividing y by x'
tan(θ) is the slope of a line that makes an angle of theta with the horizontal
Oh okay I see, thank you. There’s this one example that I’m confused at too, it says that arctan -√3 = -60 degrees. I’m confused on how it became -60 degrees?
what do you think it should be instead of -60°?
60 degrees?
Oh okay, perhaps 300 degrees, I get -sqrt(3) as well as 330 degrees
330 degrees, great
er
no
tan(330°) = -1/sqrt(3).
300 degrees is right.
and it's exactly one full turn away from -60°.
the output of arctan always lies between -90° and 90°.
Oh okay, should I subtract it 300 with 360 to get -60 degrees?
can someone explain to me why Pythagorean's theorem can't be simplified to a + b = c by taking the square root of both sides?
$\sqrt{a^2 + b^2} \neq \sqrt{a^2} + \sqrt{b^2}$
peaceGiant
ohhh i see
okay thanks
so would you be able to simplify it if it was like this (a+b)^2 = c^2?
Yeah, if that were the theorem you could, since we are assuming they are the lengths of a triangle >0
ah okay thx
You could also prove that by doing sqr(5^2+4^2), which is sqr 41, and sqr(a^2) is always a, so 41 doesn't equal to 5+4, or 9.
or sqrt(2) isn't 2
Hello, how could I find the value if I’m given sin 9pi/2? I converted it into degrees and got 810 degrees which is big, so I subtracted 360, but got 450.
dont convert it into degrees, it only makes it harder
notice that 9pi/2 is pi/2 plus itself 9 times
that means you are going 90 degrees in the unit circle 9 times
so start from the angle 0, go 90deg (or one quarter) nine times, the y-coords you end up with is the result
yeah u can subtract another 360deg again to get its position on the unit circle
Ahhh yes because pi/2 is 90 degrees. So if I go 90 degrees in the unit circle 9 times, and you said that I’ll start from angle 0 to 90 degrees. So basically I’ll go back and forth to 0 degrees and 90 degrees back and forth 9 times?
it’s two full cycles on the unit circle+ 90deg
Oh okay but why two full cycles on the unit circle?
each cycle is 2pi so 4pi would give u two cycles, 9pi/2 is 4pi+π/2 which is two cycles+ 90deg
alternatively as waler said above u can have 9 times of 90 deg, and for one full cycle u have 4 times of 90deg, so 9pi/2 gives u two full cycles+90deg
Oh okay so one full cycle is 2pi. I see now! How come that 9pi/2 is 4pi+ pi/2 = 9pi/2? How did the numerator become 9?
4pi=8pi/2
How is it still 8pi/2? 😅
u don’t know 4pi=8pi/2?
Nope, but since you said 9pi/2 is 4pi + pi/2. In order to add them, you took the LCM didn’t you? So it became 8pi/2 and pi/2. Then it’ll be 9pi/2?
yep
Oh okay thank you very much for the help! Thank you too Waler!
lcd to be exact
Icd?
lowest common denominator
Oh okay, thanks!
Oh how about if I have to find tan 7pi. Should I turn 7pi into degrees? But I only get a huge number
What should I do if I get huge numbers and I have to find sin and cos and tan? Should I subtract it to 360 until I get a number that I can find in the unit circle?
7pi means 3 whole cycles(6pi) and half a cycle(pi) around the unit circle, now if what u are trying to find is the coordinates of a point in unit circle that is being defined by "tan(7pi)" then it will be the same as "tan(pi)" and thus we can say "tan(7pi)=0/-1", (-1,0) is the coordinate
i just want to answer it, correct me guys if im wrong😅
Ah okay, Thank you very much @brazen notch
welcomee, glad to be of help
help please
Can anyone help me with question 13? @ me
Is it possible to prove that BX=CY?
for 13: which of those translations will keep the spacing of the hexagons together and get you between rows?
hello?
its more like recreational math
Need help with this question
https://cdn.discordapp.com/attachments/893758809988800582/894490825449418792/Screen_Shot_2021-10-04_at_6.25.13_pm.png
7a 7b and 7c
Maths and chemestry crossover 😳
chemestry 
Please tell hoe to approach
<@&286206848099549185>
Thanks xie
@upper karma what are your ideas
please stop trolling
I could not solve
R1, R2, r3 are radius of the circles
How? It’s a problem I made my self and I’m genuinely curious how one would solve it…
the problem is so poorly formulated that there is no question you're trolling. i'm muting you for a month.
Hahaha that question firstly doesnt belong here
A circle of radius 5cm has a chord 4cm from the centre of the circle. The length of the chord is? Use circle geometry.
->Please mention when solved!
we don't solve things for you here, but we can guide you towards a solution
⬆️ @heavy pumice
have you drawn a diagram
Bro, I don't want a solution. The answer is 6cm. I need help to understand HOW to do it
have you drawn a diagram
@heavy pumice I just did it on a piece of mail using only the description, and special right triangles. Sketch it out, you'll see it. No fancy circle theorems required.
please anyone help
@loud shard Do you know the trig identities?
$\cos(a+b) =\ cosa \ cosb - \ sina \sin b$
Pealover
does it tells something to you
yes
yes
i don’t think this is write
right
wouldn’t x be 35 and y be 40
bc same side interior angles add up to 180
2x+y = 130 2x-y=30
add the equations up and u get 4x = 180
*160
then
x = 40
so y = 50
lmao it happens
do u know how to do 2 column proofs???
no
cause u have to prov the lines to be parallel
and the alternate angle theory
requires the lines to be parallel first
HOLY SHIT
IM BRAINDED
OML
KILL ME
IM SOO STUPID
THATS FOR THE OTHER 2 LINES
omegaulul
@dire egret Find the number of sides a polygon has if the sum of the measures of its interior angles is four times the
sum of the measures of its exterior angles
let me think
I had a problem which I really don’t understand in physics that uses geometry and trigonometry. This man is standing 3 m from a kid who is 1,5 m from a mirror. The man is 1,5 m and the kid is 0,5 m tall. The eye level of the man is 1,45m and the eye level of the kid is 0,45. What is the minimum length the miroir should be for the kid to see himself completely? What is the minimum length of the miroir for the kid to see the miroir completely?
I drew out the problem but I still don’t get it
I know I have to construct right triangles
but given the eye level of the kid, it would no longer be a right triangle no?
u done thinking, i have to sleep soon
i’m sorry i haven’t learned that stuff yet 😭
oof
why can’t the mirror just be .5 meters tall?
the formula for interior angle is 180(n-2)
for sum of interior angles
and exterior add up to 360 always
is this for the question?
ye
yeah i have never even heard of that
so is it 10 sides
???
LETS GO
its 10 sides
boi
i am acting hella stupid today for sum reason
lol
i knew u could do it
cause they’re asking for the smallest miroir possible ;-;
otherwise the miroir could be infinite measures
after you made enough arguments, the last line would just be what you intended to prove
https://cdn.discordapp.com/attachments/893758809988800582/895183221627711498/Screen_Shot_2021-10-06_at_4.38.06_pm.png Can somebody give me the working out and answer for this question
@upper karma we don't give out answers here.
Ok well what about the working
giving out the working would amount to also giving out the answer
so what do you guys help with
we help you solve the problem yourself.
you tell us where exactly you're stuck (whether it is "i have no idea how to even begin" or something else), and we give you pointers in the right direction.
yeah Im done anyway, all good
Source:
I am correct at the 2nd and 4th problem in Area section?
I am not sure if bh/2 is applicable for all triangles
it should be applicable for all right angled triangles (or when u can split them into right angled triangles)
So I have the question "Find all the solutions for the equation tan(x) = -tan(2x)"
I did the following:
Looks good to me. Idk if you know unit circle stuff but you can go one step further to give x values that satisfy Tanx=sqrt3
Wtf
Nah i have been struggling with this
Yep
hmm
@lapis pine
Still no idea
kinda confused, for the y "coordinates" does the definition still hold for the distance if the x and y values are squared?
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<@&286206848099549185>
If cos(t) =
−
5
19
and tan(t) < 0, find sin(t) and cos(-t)
pythagorean theorem
cos = x/r
so construct a triangle with x = 5 and hypotenuse = 19
solve for the other leg in refernce to theta
I'm having a bit of trouble here. I know that they'll all be parallel because the lines all have the same directional vector t(d,e,f) but I'm not sure how to prove that.
<@&286206848099549185>
Okay got through the above problem but now I'm on a new one. I would appreciate the help if anyone could provide it.
<@&286206848099549185>
@sand jolt still need help?
Yes very much so.
I know how to map a line in the form of (a,b,c) + t(d,e,f) like in the previous problem but I'm not sure what to do when it's just flat on the object plane like that.
wouldn't you just take the plane going through the line in the object plane and the viewing point and then intersect it with the image plane
What do you mean?
i mean exactly what i said
we have our line in the object plane
consider the plane that goes through this line and the viewing point
this plane intersects the image plane along some line, and that will be our image
When you say "the plane" do you mean the image plane or the object plane?
Or is there a third plane?
neither
i say "the plane that goes through this line and the viewing point" and i mean "the plane that goes through this line and the viewing point"
Oh wait. I think I get what you mean.
What is the maximum number of points that two lines can intersect at?
That means that the maximum occurs when each line intersects every other line at a unique point
Yes
How many ways are there to choose 2 lines from given 5?
7?
(We are trying to find all possible combinations, choosing any two lines gives us an intersection)
So i should use. PnC?
A combination can be used here
We have 5 lines, we need to find all possible ways to choose 2
I'm grading a student's work and wanted to know if I should give this a 0 or 1 (no partial credit)
Show that if a circle and a square have the same perimeter, then the circle has the larger area
its not exactly circular reasoning, but I feel like it's bad proof writing to assume the statement is true, then equating it to another true statement
what's the total mark allotment?
this question is 1 point
and were they explicitly told in class to not start with the RTP?
RTP?
required to prove.
they weren't explicitly told
Then I'd personally give full credit cause it's "right" but add a note on proper format.
thanks
This comes with the caveat of, since you asked in a HS channel, it is a HS student and thus more likely than not is only starting proofs
what year?
Ok then yeah, full mark + note would be what I'd do
$cos(x)sin(x)+x(-sinx)(sinx)+x(cos^2(x))$
JPod
How can I simplify this down?
multiply the sins in the middle out and see if you see something
JPod
what can you factor out of the last two terms?
JPod
right, now you probably more commonly see the identity written as $cos^2(x)-sin^2(x)$
a disappointing son
👍
Disorganized
hint:
use what you know about sine and cosine values on the unit circle (reference angles)
Sin=y/r and cos =x/r
why don't you sketch all the triangles on the unit circle that reference the 60 degree triangle, from the x-axis.
There are 3 triangles (4 including the 60 degree) that do this.
Evaluate their sines and cosines.
which angles match cos(60) and sin(60)?
those are not the correct ratios, look at your notes or google them
you need to memorize the sine and cosine values of the "special right triangles" to pass this class, this is just one of the first applications
ugh, this isn't true, lol
why is TO angle bisector and OT perpendicular to PQ
It's because TP = TQ, so angle TPR = angle TQR, and then you can use similarity
For some reason I can’t find the area for this quadrilateral
I tried cutting them and finding the triangle first
Please if there is an easier way please show me
JPod
draw a line parallel to side 7.5 so it make a parallelogram with sides 5 and 7.5 then find area of triangle formed using heron's formula and find the altitude then apply the formula of area of trapezium
idk if i drew the diagram for 1 right
and 2 i got no idea where to start
for q1 i thought the stake is 10 mettrs from the fence, so idk if it creates a sector or segment
<@&286206848099549185> .-.
@tiny stump the picture isn't quite right but I am also suspicious of the claim in Question 2
Circle is fine, its the radii you drew from the chord instead of the center that are wrong
Join Mathematics voice channel
ok one minute pls
ahhhh
that makes sense
im still trying to wrap my head around the triangle formula
r^2/2 * sin(pi/2 -x)
nvm
i see it
ab is r^2
i dont quite get where the pir^2/4 came from tho...
the second line
one quarter of the area of the circle
ahhh yes
ok
ty sm
that helped alot
then u equate them and get x=-cosx
got it
ty
nop
edit: spelling, lol
njo?
ok
wait
gimme a min
so do we do the first line minus the second line?
wait a min
are u sure u dont equate them
if we dont equate them then what do we do
coz the first line is the area of the segment and the second line is also the area of the segment
then we rearrange to prove x
yes. first line equals second
my other idea is we use the trig graph?
but idk how to apply it here so i dont think we use it
i noticed i could factorise out the 1/2r^2
but i dont see how that helps
yes, you should do this
hehenrique
so factorised i got
$1/2r^2 [(pi/2 - x) - sin(pi/2 - x)]$
Kitsune
sin(pi/2 - x) =cosx coz of the graph right?
hehenrique
compound angle right
OK
that makes sense
coz sin pi/2 =1
and cos pi/2 =0
which equals cos x
ok
so we can simplify the factorised expression to:
$1/2r^2[(pi/2 - x) - cos(x)]$
YES
I GOT THAT
ty
ty sm
i felt big brain i wont lie
ty
i went the longer way i times everything by 4 then canceled 4
ty
then canceled r^2 and was left with pi on both sides
then i solved form there
glad to help. lemme see if i can figure something about question 1
ahhahah that would be great
u explained extremely as well, im thankful u didnt give me the straight up answer !
ok, in first question the whole goal is to find the area of the segment. I trust you now are able to find its area if you are given the central angle right?
so let's focus in finding the angle
ye
yep
is the area of the 1011?
fu--
i dont think it is
one min
its cosine 1/2 right
which is cos 60
so the angle is 60
check if you didnt leave a negative sign behind
so its cosA = 20^2 +20^2 - (20root3)^2 all over 2*20^2
simplifies to cosA=800-1200 all over 800
-1/2
yep
gotcha
hence A=120 degrees
i convert 120 to radians correct?
yes, 2/3 of pi
i hope thats right, i dont intend to do the calculations haha
can u flip it plz
Like?
Np
so
it says that 3costheta = 5sintheta
which means that u replace 5sintheta in the equation with 3costheta
therefore u have
.
uhhh how do i get the bot working
..
i am trying to show my work using the bot
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Ahh@void moat try idk
i will help u tho dont worry
i will make u understand the problem
Ty
i am solving the problem
then i will go step by step
@true hound the first thing i would do is replace the 5sinthetas with 3costhetas
and remeber that sec^3theta = 1/cos^3theta
Yes
Can you help me with this task, because I can't even remember how to start:
The segment CD is the height to the hypotenuse in the right-angled triangle ABC. The points M and K are the midpoints of AD and CD, respectively. If AC: BC = 7: 9 and CM = 14 cm, then the length of the segment BK is?
ex. 8
<@&286206848099549185>
can u solve?
LHS=cotx/(1-tanx)+tanx/(1-cotx) =cotx/(1-tanx)+(tanx(-tanx))/((1-cotx)(-tanx)) =cotx/(1-tanx)-tan^2x/(1-tanx) =(cotx-tan^2x)/(1-tanx) =(1/tanx-tan^2x)/(1-tanx) =(1-tan^3x)/(tanx(1-tanx)) =((cancel(1-tanx))(1+tanx+tan^2x))/(tanx(cancel(1-tanx))) =1/tanx+tanx/tanx+tan^2x/tanx =1+tanx+cotx=RHS
Hey all, I want to learn trigonometry and I have no background on it
Im doing well in algebra but I need a good source to learn trig from scratch for school and self-taught calculus
Khan academy
I am working on deductive reasoning does anyone know a good site to work on it
in geometry
<@&286206848099549185>
Is there a method that can give me the volume of overlap between two ellipsoids? So far I have discovered algorithms that can check whether two ellipsoids collide but they don't tell me the exact volume of overlap. There is also the monte carlo approach but it is not an exact solution.
can anyone help me with this one https://cdn.discordapp.com/attachments/509460208737845248/897272369893220372/unknown.png
it means the angles are equal
I was asking Sukkix/lh
i saw that emoji change /j
Hi guys,How do I need inverse trigo function for this question???
I'm not looking for the answer,but how to solve it..Thanks!
I still can’t find the area 😭
There has to be some extra information to “fix” the quadrilateral so that it has a specific area.
Is something other than the 4 sides given?
You aren’t supposed to do this by hand right?
Yes I’m not sure how to start
Two triangles on either side and trapezium in the middle
How can I get the length using the degree 79?
6sin(79) is the distance of D from AB and 7.5sin(67) is the distance of C from AB
Let foot of perpendicular from C to AB be E and D to AB be F. So, DCEF is a trapezium with height EF=9-6cos(79)-7.5cos(67) and parallel side lengths as 6sin(79) and 7.5sin(67)
Basic trigo
Pythagorean isn’t required for area of right angled triangle though
Area of DFA is (6sin(79))(6cos(79))/2
Can I use that formula for the CEB?
anyone know how to mae this in geogebra
It looks like the first part requires an inverse function. You find what A is equal to with inverse cos, then you find the function value of A halved
cos of A/2
Note that it's in quadrant 3, where cos is negative @humble minnow
You can probably just experiment with lines and such
A = 2 - 4sinx
B = 3 + cosx
A(highest) x B(lowest)
Help
A(highest)= 2+4 and B(lowest)=3-1...
is NML~PQR same as MNL ~ QPR
Anyone that may guide me through this? Idk whether this belongs to multivar calc or geometry xd
<@&268886789983436800> ban please
Guys do anyone knows about graphing in math?
try desmos
if u mean graphing functions online
ok thanks
See DM
Disorganized
Hi can anyone help me out with question 3i&ii) thanks
Sides AB and AC and median AD of a triangle ABC are respectively proportional to sides PQ and PR and median PM of another triangle PQR. Show that ∆ABC ~ ∆PQR.
Apollonius’ Theorem can help you secure the third side length
hey can anyone help with this question i have to find x
i have no idea if im in the right server for this but hopefully i am
law of cosines
use cosine rule
What is the "radius" of a heart? Thanks to Stéphane from Belgium for the suggestion!
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Are there any identities for (cosx)^3 and/or (sinx)^3? If not standalone, maybe in some type of relationship (similar to (sinx)^2+(cosx)^2=1)?
Could someone ln a hand here?
Anyone? xd
I don't know it, sorry
Say I have some substitution for cosx = u
How do I alter u so that I have a value for it when I transform cosx to cos(2x)
just use double angle...
hi, how do i tell whether or not three coordinates, for example (3, 51), (-9, -324) and (12, 204) will make a linear equation or not?
yeah i got it now thank you though!
A lot of ways. Simplest one is to check the slope of lines the points go through.
The slope is (y2 - y1)/(x2 - x1) and see if for point A and B, their slope is the same as B and C.
your segment would be something like this. perpendicular means that the angle between the segment and the y axis is 90 degrees
The question is asking you: after rotating this line around the y axis what shape does this trace out?
yep
how do you apply the 6 circular functions (e.g., cos, sin, tan, sec, csc, cot) in real life?
That sounds like a question your teacher should have answered, but you said it like a question your teacher should have assigned as homework.
Either way, here you go:
https://www.mathnasium.com/real-life-applications-of-trigonometry#:~:text=Trigonometry is used to set,a point in the sea.
Hii
I have answered it there, you can check it
Does that match the answer you were comparing it against?
