#geometry-and-trigonometry
1 messages · Page 102 of 1
I started 4 months ago because I could hardly divide and I wanted to know what people were talking about with all the X and Y and Z and symbols
Idk why but trig has been fun for me even when I hated geo out of all classes
I’ve gotten into high school geometry so far
It’s application to the real world for me personally
You can use it in aviation to find distances and slants
Yeah it’s interesting
Yep been struggling with it
what did you say? 😡
It was not bad but fucking quadrilateral messed me up😭
what's wrong with quadrilaterals
You had to remember stuff like how it’s a rhombus or if it’s a parallelogram
No their fine
Cyclic quads?
quadrilaterals that are inscribed inside a circle
A quadrilateral inside of a circle iirc
Ah
mmmhm
I remember one time getting scolded because I didnt remember the property of intersecting circles
not the regular perpendicular bisector bullshit but it was a special theorem that was key to solving a difficult problem
What makes math interesting for you guys?
I basically find it like a sandbox. It’s interesting seeing how things work like I would spend an hour on desmo and calculator seeing how theorems work
Me too,alongside how well it can describe things in the world,and it’s applicability
It never feels like a waste of time to do mathematics
It’s also like a puzzle and it feels prestigious to do higher level stuff knowing your hard work learning the building blocks got you up to that point
the puzzle solving part of it. it feel great to apply basic knowledge and concepts and mix them together to do difficult questions
Yes,and finally nailing some problem or concept you’ve been wrestling with feels amazing,like it’s trying to call you dumb and you just proved it wrong by sheer willpower and mathematics
thanks!
CAN ONE GIVE ME TIPS TO TAKE MY TRIGONOMETRY AND CONIC SECTION FROM BASIC TO ADVANCE
DRAW BIGGER CONES
[In seriousness though that's far too broad a question]
Assuming you're a high-school student (by this I mean not a university student), you can probably look up textbooks
yo so you prepping for jee right
id assume you know hindi?
theres no other way other than watching lectures and doing problems
there are a lot on youtube
see which teacher you like the best and watch the lectures
and try to find questions
THANKS BRO
OK BRO THANKS
[Also - is your CAPS lock broken or something?]
I THINK SO
his shift key is locked
His key lock is shifted

Lock's shift is keyed
anyways help for 1000000 robux
\
ok i got it nvm
wait does this mean i get 10000000 robux
What am i forgetting about this?
for angle b you can use sum of angles in a triangle
buut how do i figure that out when all i have is the 90
no look at the big triangle
6 x 1.41
6 x 1.41
I don't know if it's correct but I think it's likely
your solution is def wrong
what is the answer
4sqrt(6) ?
Nice problem 🙂
!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.
for future reference...
!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.
idk why but ts pmo now.
Guys I just thought of something
Why have so many product to sum identities when you can use a few
Example cos(9x)sin(8x)
We can change cosine into sine
sin(π/2 -9x)sin(8x)
Or sin(3x)-sin(x)
We can make it positive
sin(3x)+sin(-x)
I feel like the other identities are very useless(kind of)
Taking your argument to the extreme, I could say that all trigonometric identities are useless, as the definitions of sine and cosine alone are enough 🙂 But we don't do that, because it's much faster to use some suitable identity rather than deduce it every time it is needed. So, it is just faster and more convenient to remember as many identities as you can.
Yeah I guess you’re right
it's not about anything conceptually new but about practical convenience
Was doing a physics question and it says "inclined plane with inclination 1 in l." What does this mean? Does this refer to sin(x) or tan(x)?
Usually it would mean the slope is 1/l.
well, something went wrong 🙂 bc the chord AB is definitely supposed to be shorter than the diameter DC which is 12.
This is exactly the case when a coordinate solution is fairly short. ||If the larger circle is given by x^2+y^2=6² and r=AB/2, then the x-coordinates of the intersection points of the smaller circle with the x-axis satisfy the equation x²-x+(6²-2r²)=0 (by Pythagoras) and we know that x1=-3 and x2=4, so r^2=(6²+3*4)/2=24 and AB=2sqrt(24)=4sqrt(6).||
In convex pentagon ABCDE, AB = 1, BC = 2, CD = 3, DE = 4 and
m B mC mD = 135 . If x = AE, compute the ordered pairs of integers (p, q) such
that x^2= p+qroot2
can u help me solve it please !
btw i am new here 😊
||Draw line BF parallel to CD. The rest is easy by Pythagoras + law of cosines ||
||Construct a rectangle like the following. The rest is Pythagoras||
@civic rock i didn't quite get it dude
just a curiosity, in trig if we get confused from a question, could we make the trig functions a variable such as x or y?
nvm i dont think its a really good idea if we do that all the time
guys yk when they say in a question that circles are touching does that mean they are tangent or can they intersect
my first thought would be tangent
Generally tangent.
o ty
just making sure
coz there was this question i did where there were 2 circles with the same centre but different radii and they touched another circle
Sounds like the latter circles lies between the two concentric ones.
I need some easy to follow trigonometry books, that makes me understand concepts, and has cool and challenging problems, and also covers the high school trigonometry syllabus
hi
hello
yeah, 'touched' is the common English translation of 'tangent'
cause tangent is a Latin word
in Latin tangent literally means touching
||(it's the accusative of (linea) tangēns for all you linguistic nerds)||
the question was smc 2020 i think
lemme check
yeah question 18 of SMC 2020
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 was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
i js wanna verify, is 55º correct?
Give me like 3 minutes and I gotcha
So @visual flume your trying to find Angle RPK correct?
So you have 2 known angles, which are KMR which is 134° and the other is QMK which is 20°
wait what
so what i did is draw the center O
and kom is 134º
and qom is 20º
wait
i js got 56º
i never saw the mr=mk thing lmao
well based on iscoceles kmr rpk would be 56
but if i use inscribed angles
its 55
Due to isosceles, the arc RQM is 134°, so we have angle MKR = angle MRK = 67°, right?
Bu angle sums, then angle RMK = 46°, and angle RPK is 20°/2 more than that.
What was the argument that gave you 55°?
i used inscribed angles to get 55
but i also got 56 from iscoceles
wait have i seen u before
anyways
if you have circle center O, ROM is 2 times RKM
and draw ROM and its 20+y
its kinda confusing
and then ROK would be 206-y
so RKO would be 103-y/2
and if u add RKO to OKM u get 126-y/2
and u get the equation 252-y = y+20
y= 116
but its prob wrong
Well, your y should be 114 because the chords MR and MK are equal, so they span equal arcs.
Aren't you just trying to find the angle RPK?
Currently I'm trying to understand how No Stop got 55° for angle RPK.
Me too 💀
May I dm you?
Can't you say what you have to say here?
Wait, why would angle RKO be half of angle ROK? It is RMK that is half of ROK.
It was about the actual answer. But sure I can just say the equation.
I agree with 56° as the actual answer.
ROK is 92° and RKO is 44°, close enough to half of 92° that the mistake might only make a small difference at the end.
Hey can somone help me with mid point theorem
me too 😭
wait
hold on
i think im tweaking
oh sorry i meant (180-260-y)/2
OH
wait thats where i got it wrong
i forgot to subtract from 180
dang i lowk sold that
yeah so basicallly i forgot to subtrac t180 and got 55
its 56 either way then
thanks for helping
bro
darkest diagram ever
anyways if u look closeley u can see some lines and stuff
so in this diagram ce = eb, cd = ad
de = 1/2 ab
thus de || ab
Ye i appreciate the diagram but i understand the basics but got a super complex midpoint theorem question i opened ticket in help so just waiting there ig i could upload it here if you want
a) Calculate length of CE
hahaha
ye
omd
so bf is 15*2 = 30
my eyes have been opend
Tysm
nah
oh
currently 1am and got school tmr
cuz thats one of the speech lines in it lmao
rip
lmao
yeppp
<@&268886789983436800>
So for Self Study, Should I use one of the AOPS intro to Geometry books to learn the geometry curriculum but be well prepped for competition math?
I would recommend to use the state standard curriculum textbooks first.
BF=2GE,CE=2BF
=>BF=2(15)=30
=> CE=2(30)=60
I found the answer, it is so fun
i mean, it took me more than an hour
I think that book is very good, yes
So like glencoe?
Thank you for your response actually TBH It was kinda hard to determine which geometry book to get or find a pdf of and read as I wanted it to be rigourous yet still follow a curriculum so thank you so much.
If it follows your state curriculum then yeah. The only reason why I’m recommending it to follow your state curriculum as you’ll be knowing the necessity of what someone your school have already learned.
Haven’t seen AOPS book yet might look at it later
So if you want the information I can give it but essentially the AOPS textbooks are like harder versions of your typical geometry textbook and introduces more harder problems seen in competitions in math such as AMC for example. These do cover a geometry curriculum though unless you look at their TOC the website doesn't really explain the TOC that well of them.
Ahh then yeah if you like those advance stuff then go for it. Since it’s going in depth then yeah it will likely cover everything you usually need
Very not to scale.
But simple enough if you start by drawing DEF and then extend EF to AC approporiately and note down the various angles that are forced by the given information.
hey guys im new to trignometry and i have a question
i was calculating sin of A and uhh sin is perpendicular/hyp but i need to do sin of A so how do i know whats the perpendicular relative to angle A?
what am saying is that perpendicular for the sin of a will be the side adjacent to a or the side opposite to a
what is A? angle?
yeah
is A and a the same?
angle A
bru im retareted how tf u do ts
yeah sorry😭
the only formula for sin i know is opposite side / hypotenuse
CDE and ADE are equal
ohhh tysm
idt angles can be perpendicular. only lines do
when lines are perpendicular, they form a 90° angle
,, x+y=360^\circ-2(\bullet)-2(\measuredangle) \
z = 180^\circ - (\bullet) - (\measuredangle)
glass
,align x+y &= 360^\circ-2(\bullet)-2(\measuredangle) \
&= 2(180^\circ-(\bullet)-(\measuredangle)) \
z &= 180^\circ-(\bullet)-(\measuredangle) \
2z &= x+y
glass
quadrilaterals always have a total internal angle of 360° and for triangles 180°
Let <BAE=a and <CDE=d
=> a+d+z=180 => 2a+2d+2z=360
=> 2a+2d+x+y=360 => 2a+2d+x+y=2a+2d+z=>
2z=x+y
Was genuinely excited 😭
never trust links 💔
oh thank you
ty
Nah man, i suck at geometry
Am i weird that i can do trigs but can't do this kind of geometry😭
what geometry
it's not weird I'm kinda like that
Like this kind of geometry
maybe trig is actually is easier than geometry bc trig is limited to triangles and circles
Well that is applied trigonometry within geometry
it looks easy
I just need to learn angle theorems to improve my geometry i guess
For me it's hard💀
It's about learning a little bit of everything. I recommend that you don't be mechanical and that whenever you see a theorem, axiom, etc. try to demonstrate all those properties. That way, you will hardly forget those theorems and you will progressively improve in geometry.
for that particular problem i used facts like supplementary angles and complementary angles and a triangle always have a total internal angle of 180° and special triangles like 30°60°90° triangle
a flat line has an angle of 180°. if a line divides it, the resulting two angles will have a sum of 180° (supplementary angles)
Yeah, i just need to do a lot of practices, but currently i am just learning calc 2, is it wrong that i learn calculus without even mastering geometry (and i left behind linear algebra [like matrices, Eigenvalue])
idt u have to really master geometry
u might feel the need to go back to some concepts ig
Yeah, you are right
Geometry doesn't have much to do with calculus, but if you're learning Calculus 2, you should master functions, limits, series, and more advanced trigonometry.
maybe geometry like conic sections
clear geometry of space
but mastery isn't mandatory
the calculation is applicable within that
I haven't master series yet, currently i just want to integrate everything😂, like i still learning to derive the integral of arc hiperbolic functions
i haven't mastered series either
i just know taylor/maclaurin series and geometric series
but I don't fully grasp the concept of convergence/divergence
It is not that difficult either, summative, productive, convergence, divergence, etc.
or at least I don't, calculationwise idk
I don't even know what taylor series and mclaren series are
Ahh, so you can convert them back and forth
Wolfram Alpha doesn't understand your query!
Perhaps try rephrasing your question?
Click here to refine your query online
I learned a bit about the convergence and divergence tests from the OG chemistry tutor guy
it shows how any function can be written as a series of polynomials
,,\sum_{k=0}^\infty\frac{(x-a)^kf^{(k)}(a)}{k!} ?
glass
maclaurin series is taylor series where a=0 (radius?)
that's neat
Yeah i think, i'll learn those two series rn, thanks bro!
and the chemistry tutor guy already has videos about it👍
idk if i wrote it right. lemme check by trying jt on sine or exp. i kinda remember their series expansions
-# it's correct
i think it's fun if you try to derive it yourself
i forgot the concept behind it tho. like u start with linear approximation oh yeah
basically taylor series is a series of approximations of the function
starting with linear, then quadratic, then etc. to infinity. The more terms, the better the approximation is
that’s not true
e
U should've said lim x---->♾️ (1+1/x)^x
where the hell is geometry problem
Bro it's in persian I need time to translate it
Do u want matrix or just shapes problems?
send them so people can try them
Hm sure
Everyone
I spent a lot of time translating this question to English so u better solve the shit out of this question
Btw 18 is a wrong option it was supposed to be 10 gpts mistake
triangles ABF and BEC are similar so $\frac{BF}{CE} = \frac{AB}{BE} \implies \frac{x}{\frac{2}{3} s} = \frac{s}{2x}$
south
hang on, but isn't the question at fault cause it implies AB = AE?
Noo it doesn't say AB=AE
Lemme give you a hint
You must draw a segment from a point to another
oh that's not a right angle, my bad
Sometimes the figure looks like something else, don't be fooled by the graph.
xd
an inscribe right triangle has area π, prove that it is 3-4-5 triangle
ehm a triangle could not have area Pi
i mean a circle inside triangle has area of π
ohhh
So... do you have an idea?
???
DAMN, i am stuck, should i just answers it is not enough information?
Poncelet's theorem
Ok, when you tabulate a value of a and find the value of b, the relationship a+b = 5 will always be maintained; so with that you would demonstrate the triangle. What happens is that a and b can have infinite values, but their sum will always remain constant at 5.
Another way to demonstrate it would be to state the statement the other way around, that is, if we have a right triangle of 5-4-3, prove that the area of the inscribed circle is 1
That way it would be easier
or non-analytic functions
what is analytic function
I think it’s basically just a function where it’s Taylor series converges everywhere to the function
i see
alright that's enough #calculus or #real-complex-analysis right there
in this world of #geometry-and-trigonometry
But the point is that not every smooth (infinitely differentiable) function necessarily converges to its Taylor series. usually they don’t bring that up
yea i could see that
like 1/x?
or
maybe u could pick another radius of convergence (idk if that's the term)
No
hello, im just starting to learn geometry, what are some tools that i can use to learn it, other than khan academy, which is what im using now.
Geogebra and/or Desmos
this is probably very well known, but a cool property i found of 'skewed' (i.e effectively rotated) grids is that they have large gaps orthogonally and diagonally between any two points on the grid, despite there being points close by
Ok guys I'll send the answer now
There are 2 super ways to solve this 1 long way whoch came to mind of people and 1 is a cooler and faster way
Omg
I can't take screenshot of the question cause the site policy
This is gonna take long
Lol
Yo guys I just realized tex it is a girl cause it's pronounce is she/her
Hi, when a formula says: a sen α. It means a * sen α; or it says the sen α of a? Ty
quadri oabc is a kite because angle o=b=90, and C+A=180
So you can tell the length of CO=3,OA=4, and OA is radius, and the formula of the quart circ is πr²/4
wait for that to be a kite then oca and abc would be the same
which idk how to prove
You don't need to prove by length.
You just need to proof by angles
and that is enough
i meant angles oca and abc
-# fun fact: there used to be none
Go back learn about the property of a kite
bro
Go!!!
IT IS!!
EXACTLY
then ob would also be 4 because it isa also the radius of the circle
so oba is equilateral
which means ANGLE boa is 60º
and due to the fact that coa is 90º, cob would be 30º, and ob would be perpendicular to ca, meaning oca would be 60º
so now, we have a 30 - 60 - 90 tirangle, and skince "ocba is a kite", oc would be 3
meaning the intersection point between ob and ca , may we call it d, cd would be 3/2, resulting in od being 3√3/2, and ob SHOULD be 4 if it is a kite, but we find that 2od = ob => 2(3√3/2) ≠ 4
so it is not a kite
…
why would cd be 3/2
Why??

i got the wrong question to say you are wrong, how it is perpendicular?
one of the ways I see is to use Ptolemy's theorem
4CO + 3R = 5R
-> R = 2CO
-> R^2 + R^2/4 = 5^2
-> R = 2√5
how can it be.... Okay, i give up, i used the wrong method.
what even is ptolemey's theorem 😭
imam search
if you don't want to use Ptolemy's, you can extend BC and OA so that they intersect at D
And D will lie on the big circle by Thale's theorem
wait what this is what google showed
yep
and if you look at OCBA, you see the opposite angles add up to 180°
so it is a cyclic quad
Hhmm... my memory messed up avain
so Ptolemy is applicable here
pretty good theorem btw
ohhhh
I believe it's the fastest way to solve this problem if you don't want to deal with a gazillion similar triangles and ratios
ohhhhhh
i see
tysm!
i was trying to do it with inscribed angles all the time lol
also if it is a problem related to sum of opposing angles in a quadri then pitots theorem is the solution
I see.
anyways
wait I found an easy way without Ptolemy
CA = CE = 5
then EO * EA = EC * EB
or 2R^2 = 5(5+3)
-> R = 2√5
the chord theorem?
sorta
you can see ∆EOC and ∆EBA being similar
if we don't want to bring any cyclic quad shenanigans here
Yep, i see that.
chat im going into geometry next year is it easier than algebra 🙏
Eh. For me about the same
but for others idk
alright
This is easier.
"Use your straightedge and compass to construct a triangle, square, pentagon, hexagon, and heptagon. How many steps did each take?" i'm stuck
(regular)
btw, if u r curious which polygons are constructabld
First a Fermat prime is a prime of the form (2^2^m) + 1, where m is a nonnegative integer
Eg m = 2 gives 17 so this is a Fermat prime
i know
XD
Hi, is this exercise correct? I drew the triangle with the data, so idk if it's correct, the idea is to calculate c and Â. I think C is correct but idk Â. Ty!
In fact the angle is wrong, because I'm calculating the difference between CA and H, but idk how we can calculate te angle
it's hard to differentiate your H and A handwriting
also why not just use c for hypotenuse since it's the variable for it instead of H
It's better like that?
Yes, I think so.
a^2=b^2+c^2-2bccosa
¿250^2 = 308^2 + 396^2 -2(308*396) (cos a)? How does this gives the angle of A? It's going to give a huge number
Is there a special term for an angle θ that are defined such that it is defined for all real numbers θ
What?
I mean
in simpler terms is there a term for an angle that allows for measures greater than 360° or less than 0° (for all real numbers essentially)
unlike in elementary mathematics where angles are just defined to be not less than 0° and not greater than 360°
it's the reverse: an angle between 0° and 360° is called a principal angle
when we say angle, we mean that the angle can be any real number
oh
That depends a bit on context: in elementary geometry it will usually be implicit that the angles that are being asked about are to be beteeen 0 and 360⁰ -- or even between 0 and 180⁰, ignoring direction.
yeah we don't really need a specific name
it's pretty clear when a trig context will differ from a Euclidean geometry or an angle between two planes context
It's good to be aware of these implicit differences in convention, despite the lack of generally understood terse words for stating them.
I am gonna loose it
Hint: Lots of ||central angle theorem||. All five points ||lie on the circumcircle of the square||.
Yea i am just plain stupid, so can you explain it to me ?
Do you know the central angle theorem?
yea but i cant see any of it here
Suppose ABCD is already drawn, then the central angle theorem tells you where to find all the possible locations for a point E where the directions to C and D differ by 45°.
Namely, since E is to the left of CD, it must be on a circle that passes through both of C and D, and whose center sees C and D separated by 90°. And that circle can only be the circle that passes through all of A, B, C, and D.
is that what you mean ?
Yes.
oh. yea i get it now
It doesn't look very circular, but then again the square doesn't look very square to begin with ...
It's not any worse than the original diagram, is what I said. :-)
And now you can find angle DEA, and then you're almost done.
the rest is easy, I just didnt see that inscribed angle
yes, it's because angle DEC = angle DBC = 45 degrees, so the converse of the angles in the same segment theorem implies that D, E, B, C are concyclic
and you can similarly observe angle DCB + angle DAB = 180
oh yeah and there's also a unique circle through 4 points if they are cyclic, so the two circles are the same
no need for all that, since I got angle DEA, and DAE is 90+25 I can minus all that from 180 and get angle ADE
I know just re-explaining why exactly you can draw a circle through all these points
oh, ok thanks !
(I didn't go that way, by the way -- instead I looked for a point O on the perpendicular bisector of CD such that angle COD is 90°).
Am i wrong or is this exercise is wrong? where x+2w = 500 feet of fencing and my area is x*w but since x+2w = 500 <-> w = (500-x)/2 then A = x(500-x)/2 and 0 < x <500
the author's answer assumes we also add fencing to the river side, right?
you are wrong
the question says that
x is the length of the side perpendicular to the river
ahhh, my bad
you have the wrong location of x in your diagram
i assumed it was parallel, lol
thank god i'm reviewing my knowdledge of calculus before taking the real analysis course
i'll assume i'm doing something wrong again.
my cylinder will be composed of 2 circles and a rectangle, the two circles are 2(2*pi*(r^2)) and the rectangle is 2*pi*(r)*h so the total are of material is 100 = 2(2*pi*(r^2)) + 2*pi*(r)*h, if i solve for h i get h = (50-2*pi*r^2)/pi*r so my volume is V = (2*pi*r^2) (50-2*pi*r^2)/pi*r = 100r - 4*pi*r^3
but the result is half that, what am i doing wrong?
maybe i have to assume it's not a rectangle but a square?
you double counted the circles
don't i need two circles to make a cylinder?
yes, but you doubled it twice
area of one circle is pi * r^2
for two, it's 2 pi r^2
but you had **2 ** (2 pi r^2)
ahh, right, thank you, yeah, it's just that forgot the formulae for the area of a circle
i did something like
and counted two triangles instead of one
the area was 2(pi)(r^2)/2 <-> (pi)r^2 not 2(pi)r^2
thank you
Is there anyone available to aid in my understanding of trig func verification?
It is part of an exam, so I undestand if it crosses moral boundaries; however, we are allowed to seek help as long as we give credit.
write sin2x as 2sinxcosx and then write tan as sin/cos then you get 1/cos^2 = sec^2
Man, I just realized that I posted the wrong problem, already got the answer SEC^2(theta)
Thank you so much for helping!
no worries
8 pts is a bit much for a two to three line solution, but it could be just me
I dont understand how you know so much, when you have such little context.
how do u find the coordinates of point k
It asks for approximate coordinates, so you're just supposed to eyeball it using the grid lines.
the x and y int right?
They shouldn't be integers, if that’s what you're asking.
I don't immediately recall a more formal English word for it than "eyeball", sorry.
The x-coordinate looks to me like it's about a third of the way from -0.8 to -1.0.
The y-coordinate looks about halfway between 0.4 and 0.6.
Ok
Do you have your unit circle?
Cos = x
Sin = y
You can plug them into your calculator for the approximate values
(-0.866,0.5)
yes
Sorry, ill stop now
no need to apologise btw
I know, I want to help but don't want to give inaccurate info, so I kept sending before I checked, lmao.
Oh
Ahh thx
But doing that with the calculator was the next part of the exercise, so the initial question that only asks for approximations must be about just reading the coordinates off the grid by eye.
cos = x, sin=y?
ye u find the second and third part to find the x and y coordinates
without them, i cant answer the first qs
u cant find the points by eye, would've gotten it wrong
it would be like (-0.8,0.5)
idk why its rounded to 3 decimal places
-0.866
You're not being asked to find the point to 3 decimal places by eye.
That's the follow-up questions where it says to use a calculator.
To find the intersection you would make the equations of both graphs equal each other, such that sqrt(1-x^2) = tan(-pi/6)x
Which would just simplify it sqrt(1-x^2) = (-1/sqrt(3))x . Is this right way to find it asw?
The first question is just to approximate the coordinates, and (-0.8,0.5) would be reasonably good answer to that -- although the x-coordinate is obviously a bit to the left of the -0.8 grid line, so I would say something like -0.9 or -0.85 or -0.8666.
oh alright
The exact coordinate is -sqrt(3)/2 = -0.8660254... so neither -0.85 nor -0.87 would be that much off for an approximation by eye.
ohhh i get it
The only way the entire exercise makes sense to me is that it wants you to have some experience both with reading approximate coordinates out of a random graph by eyeballing the distance from the gridlines, and with computing them to greater precision with a calculator.
Both these skills are important; they can serve as checks on each other.
Can anyone help me understand how to apply trigonometry formulas while solving problems?
Anyone?
@swift ibex u mean these?
Hii sorry for replying late
Yep
You will be given an angle say 30° and a side's length say 4 cm and will be asked to calculate the length of remaining sides
Now, firstly you will need to look if the given side is opposite to the given angle or adjacent or hypotenuse
Okay
Actually I did some of trigonometry but as lack of practice I forgot how to solve
suppose you find the given side is adjacent and you are asked to find the opposite side, just look for the formula that includes adjacent and opposite sides,i.e., tan and use it
you write tan 30° = opposite/4 cm
then either you remember that tan 30° is 1/√3 or we can say √3/3 and substitute for it there and get the answer or you can use calculator to find tan 30° if it's allowed
Approximate does not mean to read by "eye"
When you use pi, to get an answer you are only using a very small part of the actual number. I believe that's what it means by approzimate.
Okay
you will be given 2 of any three things in formulas mentioned here and you will be asked to calculate the third which i told you how to do
aah yea tropo's right first one is supposed to be done by looking, i think goal is to verify that sin, cos give coordinates of a point on unit circle, and even better exact coordinates which we can't find by just looking
It's the only possible meaning that makes sense to me in this context where they ask for "approximate" coordinates as a separate question before asking for 3-decimals approximations by calculator.
Here is problem I got in my book
A ladder is placed at an angle of 60° with the ground in the window of our house. If the ladder is 2√3 meters long, draw a picture and calculate how high our window is from the ground.
I did use this
Perpendicular= Ab , land=Bc, hypotenuse=Ac
Sin60°=Perpendicular/hypotenuse
√3/2 = Ab/2√3
Abx2 = 2x3
Ab = 2x3/2
Ab = 3cm
@worthy eagle
I understand why you would see it that way.
I really think the problem is poor due to the it causing such confusion.
oh u did some work let me check
yes good
it's correct
I don't understand why did you use Ab, Bc, Ac for perpendicular, base and hypotenuse?
is there any reason or you just picked it randomly
I mean I would normally use variables like A, B, C here or just P, B, H or something like that
I think he meant AB, BC, AC -- he has named the corners of the right triangle A, B, and C.
oh
(Where B is the right angle, and C is where we measure the varying angle).
ok
This goes to show that the "draw a picture" is an important part of the exercise, and you need to show your drawing together with the rest of the work in order for readers to make sense of it.
(It doesn't quite sound right that the window is only 3 cm off the ground, however).
oh units
@swift ibex read this and remember units, ladder's length was in meters not cm
sry for ping(tropo), mb
My teacher actually wrote them to make me understand better so I kept using them (sorry for bad handwriting)
Mb
Yep
Can you help me with this ones
If xsin45° cos45° tan 60° = tan²45° - cos 60°, find the value of x
If x sin 60° cos² 30° = tan²45° sec60°/cosec60°, find the value of x.
@worthy eagle
Yep
then just write their values there and then solve for x
it will become a linear equation of form
ax+b=0
Okay I'll try solving it
can anyone take a look of this problem, i already solved it but i'm still looking for better and simpler solution.
can you show how you solved it
see
this was one more way to do it but both ways look equally time taking
if we let 5 points make a pentagon then does there always exist a triangle with corners on these 5 points, such that the triangle at least has half the pentagon area?
help pls
im cooked
i got angle bad is 45 😭
tryna use angle chasing to solve for x (which is dp probably)
notice anything about ∆ABD and ∆APC?
uhhhhhhhhhh
UHHHHHH
UHMMMMMMMMMMMMMM
ERMMMMMMMMMMMMMMMMMMMMMMM
theyre similar?
idk
im tryna use cyclic quadrilaterals to make abpc
why are they similar then?
thtas how i got bad is 45 😭
well all i know is angle bad = angle pac
dang it my pens broken
what about angles ABD and APC?
hold on imma try to fix my pen 😭
yo we left angles in 2024
ok finally fixe dmy pen
answer my question instead gng 🥺
dell
it’s not what im initially trying to solve but I think that should be easier?
no, take the regular pentagon for instance
well I have this question where you place 5 points and the 10 triangles that u can make all have area > 2
and u gotta prove at least one has an area of 3
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
if u place them in a pentagonal pattern u know the pentagon will have an area 9>=A>6 cuz it can be made from 3 triangles and u don’t assume a triangle has an area that’s greater than 3 initially
if its minimal then a triangle must be at least half
if the thing holds right
so if this doesn’t hold then the problem doesn’t hold?
@civic rock
hell no.
every time i understand it now, i have to go somewhere
like i JUST finished getting EVERY single angle and i had to go cut my hair
and i js came and got 3/5
is it ✅ 😀
or ❌ 😡 👎
The way you did the 2nd statement seems the fastest to me, using the law of sines and expressing the angles in terms of C, you could also derive the function to find its minimum
is cos always x and sin always y?
would u find qs like this on the SAT
like would you find a similar question like that on the SAT math section?
oh wait nvm
its alr
:V
just use ∆ABD ~ ∆APC
yipeee
i see, thx
Thx master
Mathster*
jajajaja
Hey everyone, im gonna be taking geometry this year and im pretty nervous, i did well with Algebra1 and i take algebra2 after geometry, anyways i havent really done anything geometry related sense like 8th grade and im gonna be in 10th and id like to start the year off without feeling like im going into geometry blind😅 if anyone is willing to dm me and give me some pointers or a rundown of geometry and some advice id greatly appreciate it 🙂
My advice is... 🤔🤔🤔
I don't know.
What??
think of illuminati every time a triangle appears 
Well, let me give you formula of to learn smoothly:
Success=RCD/S
R is for Reading C is for Confident and D is Don't give a damn about fail.
And S is S**ess
So... the more you don't give a damn about being fail, the more you will be succeed at Something.
But still you need to read and confident (trust yourself)
Good luck buddy 🤞
can anyone help me on the problem,pls, finding the maximum of y
Rewrite it as this. ||Then use sqrt(13)<4.||
here is another general method
but yes the way above is particularly neat
derivetive?
can someone explain to me the sine sum and sine difference formula
i dont understand where cosine comes from
why does cosine appear
Do you want derivation?
I can send you a derivation by diagram video, you will understand how cos came, wait a minute.
so u can only understand where cosine comes from if u know derivatives?
Derivation, not derivative
"Derivation" of a formula refers to the process of deducing or obtaining a formula from a set of established principles, laws, or simpler equations using logic and mathematical steps.
I hope you understand now, watch the Vedio and I think it will clear your doubt
wait I have one question
is the two definitions of deriviation
something u learn in calculas
or is the
second meaning
to the thing
the proof thing
something u learn
earlier
The process of deducing something from already known facts is called derivation. This meaning is not at all related to calculas. So don't confuse yourself.
oh man, when he got confused with this. My brain also confused 'derivative' with 'derivation'
when he used 'derivatives'
big shame
derivation is a set of steps to arrive at some identity, formula or other result
Though, just to keep everyone on their toes, a "derivation" can also mean a linear operator satisfying f(ab) = f(a)b+af(b).
yess sure
terms confusement 

how can i do this problem?
A triangle's area is maximal when its height is maximal, i.e. it is a right triangle and its side is a diameter..
okayy thanksss
Hey could someone help me with this. Ik im probably smooth braining it it's been a long day but I have to prove that ABCD is a parallelogram
||you start by proving AQB congruent to CSD then prove PBC congruent to RDA||
||Try proving that PBC is congruent to RDA, then use CPCTC.||
What how to mark spoiler
use || on both ends of your text
yes
Ok thanks!
anyone here read or is reading the book "Basic Mathematics" by Serge Lang
Thanks so much
Hello, how are you? . Where on the server do I ask about books on Euclidean geometry? I'm looking for it for the first time.
Welcome to mathcord Stiven 
@cinder ledge welcome to the mathcord c:
Ty
hii im a tad confused
if the circle is used for angles, why is the triangle important and how is it related to this idea
idk but i know u can form triangles in the unit circle
yo guys help i cant beat this level on geometry dash

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 was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
Can u draw the figure
Hey guys these two problems of my trigo homework (10th grade) are really challenging and absolutely beats me, any kind of help will be highly appreciated
Hey
Hello
n or o?
Both actually
ok. we can use some rules with the sin: sin B - cosB = sen A while sin B + cosB = cosA
This is a proportion
So its just multiplying
But sinA/cosA is jus TanA
Yes, but that doesn't mean that sinB - cosB = sinA (i got confused)
What have I done?!
Still couldn't solve the second one :/
Give me a sec
I thought tanα=tan(β-π/4), then cosα=±cos(β-π/4).
while sinα+cosβ=√2cos(β-π/4).
oh no
sinβ+cosβ=√2cos(β-π/4).
k sin(a) / k cos(a) = (sin(B) - cos(B)) / (sin(B) + cos(B))
sin(B) - cos(B) = k sin(a) ...(²)
sin²(B) + cos²(B) - 2 sin(B) cos(B) = k²sin²(a)
1 - 2 sin(B) cos(B) = k²sin²(a) -> (1)
sin(B) + cos(B) = k cos(a) ...(²)
sin²(B) + cos²(B) + 2 sin(B) cos(B) = k²cos²(a)
1 + 2 sin(B) cos(B) = k²cos²(a) -> (2)
(1) + (2)
2 = k²sin²(a) + k²cos²(a)
2 = k²(sin²(a) + cos²(a))
2 = k²
k = ±sqrt(2)
sin(B) + cos(B) = ±sqrt(2) cos(a) (Proved)
Thanks y'all
idk how the polygon even is whether its a regular polygon or some other type of polygon
ohhhhhhh
oh so they are related
ya like what frances said
guys i have two exams for both geometry semesters tomorrow whar do i do 😭
learn from your mistakes
how to do trigonometry easily i m in class 10
help me
i have problem with algebraic identity in trigo
show the specific problem
many of those trig identity proofs involve the use of
conjugates and pythagorean trig identities
!show
Show your work, and if possible, explain where you are stuck.
i want to learn how to solve a question in trigo
like how to make a path
to convert ratios
too vague, the topic is too broad
show specific questions
What would that mean? You should realize by yourself that your questions are extremely vague...
which ratios do you need help remembering?
ah okay, well for cosec and sec
they start with C and S respectively
swap them around, so S and C
so then cosec = 1/Sin
sec = 1/Cos
cot = 1/tan cause both cot and tan have the letter T
hope these mnemonics help!
the more you practice non-calculator the easier it will become
just trust
thanks bro
yeah all of the tangent values (and thus cotangent) don't have any 2s
for tan it's 0, 1/sqrt(3), 1, sqrt(3), infinity
so tan is increasing
i know this
(cotangent is decreasing, the reverse order, but don't worry about that for now)
yep for first quadrant ofc
but i have a doubt in identity sinA=sin(180-A)
oh, have you learned the unit circle yet?
not learned but know it
okay, so just to recap
is this for only sin or all ratio
cos(theta) = x-coordinate
sin(theta) = y-coordinate
sin and cos
but all ratios come from sin and cos anyways
but if i put A=180 this is false
bcz cos 180=-1
but in this formula it will be cos 0 = 1
no! that formula does not apply to cos
the correct one for cos is cos(-x) = cos(x)
this is the picture proof for sin(180 - x) = sin(x)
i still have like 6-7 months before boards
ahhhh okay
you have plenty of time don't worry
but there is like 15 chapter in 10th class
keep making progress on maths, also your other subjects ofc
my maths marks are not good or else in othere subject i m in top 3 students
no but i really like coding AI ML DL which require a lot of maths
I think there's a difference with the maths you need for coding and the maths you're learning in school
not exactly the content, but the way it's taught and how the knowledge gets applied, such that school really kills learning
in coding i require like PnC
honestly just try to do well enough to get into those uni programs
exactly and you're never, or rarely, going to put a married couple in some seats right
but then there might be some coding scenario that is similar
you know there is an institute in india which has only one subject
MATHS
and a student got a package of 60LPA
crazy
Hello
A bit
Yeah well it's the top private eng college 
Getting in is not too easy
What grade are you in
ik
Ah, you still have time then
what about you
I'm in uni
i think you are in 3rd year
No, 1st year
fresher
Yes
which college
Why go for BITS then?
BITS isn't in Chennai 😭
Not doxxing myself, lol
BITS is always a secondary target
And hyderabad (and dubai)
And Dubai
why secondary?
Because it doesn't offer as much ROI as a good NIT or IIT might
bye guys let me go i have to do worksheet and work of triangles

i knew you were indian
whats this then
Hellooo
if he was indian why would he ask someone else for help with indian stuff
also having BITS as your goal in 10th grade is stupid
should aim for iits and nits since they are better for job placements which the person cares about lol
your point is true tbh
the problem is competition
jee given by more than 12 lakhs students
meanwhile bitsat maybe 6-7 lakhs
Uhh
Bits is a single college
Jee offers admission to multiple colleges
It evens out
why are you aiming lower though
if aim for iit, you have a better chance of geting into bits
aim for bits and you would prep less
Yeah but if we drawn PQ and MN is such a way that QM is perpendicular on PQ.i.e. then we can find the R+S easily
I couldnt come up with anything else
Since they didnt specify how the segments would be arranged exactly, we can draw one which can actually give an answer ,i suppose
I came up with something ↓
Begin by drawing a seven sided regular polygon, you only drawing a regular polygon for your reference. Just remember to show PQ parallel to NM in this diagram.
Now, extend MS and QR and let O be the point where they meet.
Extend NM and PQ and draw a perpendicular line from O to the extended NM and PQ.
Now you got 2 right triangles. Mark angle Q = 98° and M = 111° and use 'sum of all angles on a line = 180°' and 'sum of all angles in a triangle is 180°' to find your answer.
you can send a diagram so that I can tell you if you are doing it right
That's a vey cool wayy,thanks!
Also there is already a vertice named O in the polygon,so it should be named as something else
does anyone have any good youtube videos to learn how to do statement reason cus im talking geo next year and I havent done statement reason in a while and I dont know how I should learn it so youtube would be good or any other resources
Hi
For the vertex form if it’s like x - 3 + 2
Would the vertex be (3, 2)
And if it was the opposite like x - +3 + 2 the vertex would be (-3, 2) right
Sorry I posted it in the wrong channel
you should never drop the ()^2
otherwise you'll confuse everybody
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/
cmi?
yo is that 10th ncert by any chance
in 8th, you just open the squares and you will see general properties like sin^2x+cos^2x=1 pop up
You can try converting LHS to sin, cos and then multiplying and dividing LHS with the denominator of RHS so the denominator on both sides become same and solve the rest to make the numerators same.
For example in iv,
(1+secA)/secA
= (cosA+1)
= (1+cosA) (1-cosA)/(1-cosA)
= (1-cos²A)/(1-cosA)
= sin²A/(1-cosA)
yes
what are you typing so long
discord is bad at showing when someone is actually typing. if i type one letter and erase it it will still show me as typing for some time
but this multiplying and dividing thing doesn't work always, just tried on viii and it's getting very long,
viii is pretty simple just expand the square
actually I do solving on mobile by typing, not on paper so it shows me typing for very long
ohh ok
man these are so nostalgic
things were so much simpler in 10th
yes, converting everything to sin, cos makes it unnecessarily long
hmm ok
it look simpler now for me as a first time VERY HARD
true it wasnt that easy when i first did it
just do some practice and youll start to see certian patterns
no like in vii part
i have a solution to divide all by sin A
both numerator and denominator
first we will take common sin from numerator and cos from denominator
then divide
instead of dividing take sin common from numerator and cos from denominator and keep it as tanA
ye
ohh damn
i can't afford this much time on a question of 2-3 marks in boards
