#geometry-and-trigonometry

1 messages · Page 102 of 1

dense escarp
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Yeah maths is surprisingly very fun

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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

twin depot
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Idk why but trig has been fun for me even when I hated geo out of all classes

dense escarp
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I’ve gotten into high school geometry so far

twin depot
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ahhh nice

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Geometry is kinda a bummer

dense escarp
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You can use it in aviation to find distances and slants

twin depot
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Yeah it’s interesting

dense escarp
civic rock
twin depot
civic rock
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what's wrong with quadrilaterals

twin depot
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You had to remember stuff like how it’s a rhombus or if it’s a parallelogram🫩

civic rock
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oh I thought you're talking about random quads lol

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or cyclic quads

twin depot
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No their fine

dense escarp
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Cyclic quads?

civic rock
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quadrilaterals that are inscribed inside a circle

twin depot
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A quadrilateral inside of a circle iirc

civic rock
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I remember one time getting scolded because I didnt remember the property of intersecting circles

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not the regular perpendicular bisector bullshit but it was a special theorem that was key to solving a difficult problem

dense escarp
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What makes math interesting for you guys?

twin depot
dense escarp
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It never feels like a waste of time to do mathematics

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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

dire jackal
dense escarp
clear sleet
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thanks!

agile glen
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CAN ONE GIVE ME TIPS TO TAKE MY TRIGONOMETRY AND CONIC SECTION FROM BASIC TO ADVANCE

pale sentinel
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DRAW BIGGER CONES

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[In seriousness though that's far too broad a question]

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Assuming you're a high-school student (by this I mean not a university student), you can probably look up textbooks

dire jackal
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id assume you know hindi?

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theres no other way other than watching lectures and doing problems

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there are a lot on youtube

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see which teacher you like the best and watch the lectures

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and try to find questions

agile glen
pale sentinel
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[Also - is your CAPS lock broken or something?]

upper karma
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I THINK SO

civic rock
pale sentinel
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His key lock is shifted

civic rock
visual flume
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Lock's shift is keyed

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anyways help for 1000000 robux

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ok i got it nvm

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wait does this mean i get 10000000 robux

prime gyro
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What am i forgetting about this?

civic rock
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for angle b you can use sum of angles in a triangle

prime gyro
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buut how do i figure that out when all i have is the 90

civic rock
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no look at the big triangle

prime gyro
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OH CRAP

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I SEE IT

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thank you so much

quiet herald
quiet herald
quiet herald
civic rock
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your solution is def wrong

quiet herald
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xdxd

quiet herald
summer cradle
west narwhal
alpine cargo
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its a basic pythagorean. c^2=a^2+b^2

dark sparrow
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!nosols

lime crownBOT
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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.

dark sparrow
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for future reference...

dark sparrow
lime crownBOT
alpine cargo
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idk why but ts pmo now.

deft sail
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Guys I just thought of something

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Why have so many product to sum identities when you can use a few

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Example cos(9x)sin(8x)

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We can change cosine into sine

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sin(π/2 -9x)sin(8x)

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Or sin(3x)-sin(x)

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We can make it positive

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sin(3x)+sin(-x)

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I feel like the other identities are very useless(kind of)

upper echo
# deft sail 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.

dark sparrow
karmic rover
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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)?

grave pond
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Usually it would mean the slope is 1/l.

upper echo
# alpine cargo

well, something went wrong 🙂 bc the chord AB is definitely supposed to be shorter than the diameter DC which is 12.

upper echo
# visual flume \

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).||

visual flume
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lmao why so many replies

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but anyways i also got 4√6

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thanks guys

brittle sluice
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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 😊

upper echo
civic rock
brittle sluice
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@civic rock i didn't quite get it dude

torpid current
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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?

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nvm i dont think its a really good idea if we do that all the time

gentle canyon
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guys yk when they say in a question that circles are touching does that mean they are tangent or can they intersect

knotty quiver
grave pond
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Generally tangent.

gentle canyon
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o ty

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just making sure

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coz there was this question i did where there were 2 circles with the same centre but different radii and they touched another circle

grave pond
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Sounds like the latter circles lies between the two concentric ones.

rancid dragon
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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

hearty wagon
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hi

brittle sluice
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hello

obsidian harness
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cause tangent is a Latin word

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in Latin tangent literally means touching
||(it's the accusative of (linea) tangēns for all you linguistic nerds)||

gentle canyon
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lemme check

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yeah question 18 of SMC 2020

visual flume
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!status

lime crownBOT
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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
visual flume
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i js wanna verify, is 55º correct?

ancient crescent
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So @visual flume your trying to find Angle RPK correct?

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So you have 2 known angles, which are KMR which is 134° and the other is QMK which is 20°

visual flume
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wait what

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so what i did is draw the center O

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and kom is 134º

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and qom is 20º

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wait

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i js got 56º

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i never saw the mr=mk thing lmao

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well based on iscoceles kmr rpk would be 56

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but if i use inscribed angles

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its 55

grave pond
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Due to isosceles, the arc RQM is 134°, so we have angle MKR = angle MRK = 67°­, right?

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Bu angle sums, then angle RMK = 46°, and angle RPK is 20°/2 more than that.

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What was the argument that gave you 55°?

visual flume
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i used inscribed angles to get 55

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but i also got 56 from iscoceles

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wait have i seen u before

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anyways

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if you have circle center O, ROM is 2 times RKM

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and draw ROM and its 20+y

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its kinda confusing

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and then ROK would be 206-y

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so RKO would be 103-y/2

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and if u add RKO to OKM u get 126-y/2

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and u get the equation 252-y = y+20

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y= 116

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but its prob wrong

grave pond
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Well, your y should be 114 because the chords MR and MK are equal, so they span equal arcs.

ancient crescent
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Aren't you just trying to find the angle RPK?

grave pond
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Currently I'm trying to understand how No Stop got 55° for angle RPK.

ancient crescent
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Me too 💀

grave pond
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Can't you say what you have to say here?

grave pond
ancient crescent
grave pond
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I agree with 56° as the actual answer.

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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.

zealous trout
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Hey can somone help me with mid point theorem

visual flume
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hold on

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i think im tweaking

visual flume
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OH

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wait thats where i got it wrong

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i forgot to subtract from 180

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dang i lowk sold that

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yeah so basicallly i forgot to subtrac t180 and got 55

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its 56 either way then

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thanks for helping

visual flume
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bro

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darkest diagram ever

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anyways if u look closeley u can see some lines and stuff

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so in this diagram ce = eb, cd = ad

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de = 1/2 ab

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thus de || ab

zealous trout
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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

visual flume
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sure

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ill try but fail

zealous trout
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a) Calculate length of CE

zealous trout
visual flume
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60?

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cuz

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if u take

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ehm

zealous trout
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ye

visual flume
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triangle bfd

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u see that it has a midpoint thing

zealous trout
#

omd

visual flume
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so bf is 15*2 = 30

zealous trout
#

my eyes have been opend

visual flume
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yessss

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wait dy play doom

zealous trout
#

Tysm

zealous trout
visual flume
#

oh

zealous trout
#

currently 1am and got school tmr

visual flume
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cuz thats one of the speech lines in it lmao

visual flume
zealous trout
zealous trout
civic rock
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<@&268886789983436800>

jagged geyser
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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?

twin depot
upper karma
upper karma
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I found the answer, it is so fun

upper karma
#

i mean, it took me more than an hour

maiden brook
jagged geyser
# maiden brook I think that book is very good, yes

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.

twin depot
# jagged geyser So like glencoe?

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.

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Haven’t seen AOPS book yet might look at it later

jagged geyser
twin depot
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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

meager flax
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Here's a hard math question

grave pond
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Very not to scale.

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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.

iron orchid
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hey guys im new to trignometry and i have a question

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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?

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what am saying is that perpendicular for the sin of a will be the side adjacent to a or the side opposite to a

iron orchid
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yeah

knotty quiver
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is A and a the same?

iron orchid
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angle A

cosmic rover
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bru im retareted how tf u do ts

iron orchid
knotty quiver
cosmic rover
knotty quiver
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idt angles can be perpendicular. only lines do

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when lines are perpendicular, they form a 90° angle

knotty quiver
somber coyoteBOT
knotty quiver
#

,align x+y &= 360^\circ-2(\bullet)-2(\measuredangle) \
&= 2(180^\circ-(\bullet)-(\measuredangle)) \
z &= 180^\circ-(\bullet)-(\measuredangle) \
2z &= x+y

somber coyoteBOT
knotty quiver
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quadrilaterals always have a total internal angle of 360° and for triangles 180°

upper karma
potent furnace
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guys check out my geometry-based mario game i made in desmos

dire jackal
#

respectfully i hate you

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but good bait

graceful crag
mystic umbra
#

never trust links 💔

edgy osprey
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Nah man, i suck at geometry

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Am i weird that i can do trigs but can't do this kind of geometry😭

fresh birch
knotty quiver
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it's not weird I'm kinda like that

edgy osprey
knotty quiver
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maybe trig is actually is easier than geometry bc trig is limited to triangles and circles

edgy osprey
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Yes

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like geometries in like andy's video (andy math)

fresh birch
knotty quiver
edgy osprey
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I just need to learn angle theorems to improve my geometry i guess

edgy osprey
fresh birch
knotty quiver
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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

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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)

edgy osprey
knotty quiver
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idt u have to really master geometry

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u might feel the need to go back to some concepts ig

edgy osprey
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Yeah, you are right

fresh birch
knotty quiver
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maybe geometry like conic sections

fresh birch
knotty quiver
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but mastery isn't mandatory

fresh birch
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the calculation is applicable within that

edgy osprey
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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

knotty quiver
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i just know taylor/maclaurin series and geometric series

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but I don't fully grasp the concept of convergence/divergence

fresh birch
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It is not that difficult either, summative, productive, convergence, divergence, etc.

knotty quiver
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or at least I don't, calculationwise idk

edgy osprey
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I don't even know what taylor series and mclaren series are

knotty quiver
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basically any function can be written in taylor series form

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it's fun to do

edgy osprey
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Ahh, so you can convert them back and forth

knotty quiver
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I've forgotten how to write it lowkey

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,w taylor series

somber coyoteBOT
edgy osprey
knotty quiver
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it shows how any function can be written as a series of polynomials

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,,\sum_{k=0}^\infty\frac{(x-a)^kf^{(k)}(a)}{k!} ?

somber coyoteBOT
knotty quiver
edgy osprey
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Yeah i think, i'll learn those two series rn, thanks bro!

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and the chemistry tutor guy already has videos about it👍

knotty quiver
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idk if i wrote it right. lemme check by trying jt on sine or exp. i kinda remember their series expansions

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-# it's correct

knotty quiver
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i forgot the concept behind it tho. like u start with linear approximation oh yeah

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basically taylor series is a series of approximations of the function

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starting with linear, then quadratic, then etc. to infinity. The more terms, the better the approximation is

maiden brook
knotty quiver
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ah yeah, probably non differentiable ones

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since the series involves derivatives

potent furnace
#

e

meager flax
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I have more and harder ones

meager flax
upper karma
#

where the hell is geometry problem

meager flax
#

Bro it's in persian I need time to translate it

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Do u want matrix or just shapes problems?

fresh birch
meager flax
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Hm sure

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Everyone

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I spent a lot of time translating this question to English so u better solve the shit out of this question

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Btw 18 is a wrong option it was supposed to be 10 gpts mistake

obsidian harness
somber coyoteBOT
obsidian harness
#

hang on, but isn't the question at fault cause it implies AB = AE?

meager flax
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Noo it doesn't say AB=AE

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Lemme give you a hint

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You must draw a segment from a point to another

fresh birch
obsidian harness
fresh birch
upper karma
#

an inscribe right triangle has area π, prove that it is 3-4-5 triangle

fresh birch
upper karma
fresh birch
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ohhh

upper karma
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So... do you have an idea?

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???

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DAMN, i am stuck, should i just answers it is not enough information?

fresh birch
fresh birch
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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.

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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

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That way it would be easier

maiden brook
knotty quiver
#

what is analytic function

maiden brook
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I think it’s basically just a function where it’s Taylor series converges everywhere to the function

knotty quiver
#

i see

maiden brook
# knotty quiver i see

But the point is that not every smooth (infinitely differentiable) function necessarily converges to its Taylor series. usually they don’t bring that up

knotty quiver
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yea i could see that

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like 1/x?

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or

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maybe u could pick another radius of convergence (idk if that's the term)

maiden brook
real scroll
#

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.

spiral lodge
#

Geogebra and/or Desmos

quaint chasm
#

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

meager flax
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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

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Omg

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I can't take screenshot of the question cause the site policy

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This is gonna take long

fresh birch
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Lol

meager flax
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Yo guys I just realized tex it is a girl cause it's pronounce is she/her

analog maple
#

Hi, when a formula says: a sen α. It means a * sen α; or it says the sen α of a? Ty

visual flume
upper karma
# visual flume

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

visual flume
#

which idk how to prove

upper karma
#

You just need to proof by angles

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and that is enough

visual flume
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i meant angles oca and abc

upper karma
#

You mean, oca and acb?

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You don't need to

knotty quiver
visual flume
#

bro

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wait

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i think

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ocba cant be a kite

upper karma
#

Go back learn about the property of a kite

visual flume
#

bro

upper karma
#

Go!!!

visual flume
#

it cant be a kite

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look

upper karma
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IT IS!!

visual flume
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if it is a kite

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oa is 4

upper karma
#

EXACTLY

visual flume
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then ob would also be 4 because it isa also the radius of the circle

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so oba is equilateral

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which means ANGLE boa is 60º

upper karma
#

BECAUSE IT IS A KITE

visual flume
#

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

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so now, we have a 30 - 60 - 90 tirangle, and skince "ocba is a kite", oc would be 3

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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

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so it is not a kite

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fresh birch
upper karma
#

Just where you got cd=3/2

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there must be a reason

visual flume
#

how old ru

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search up 30-60-90 rule

upper karma
civic rock
#

one of the ways I see is to use Ptolemy's theorem

civic rock
upper karma
#

how can it be.... Okay, i give up, i used the wrong method.

visual flume
#

imam search

civic rock
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if you don't want to use Ptolemy's, you can extend BC and OA so that they intersect at D

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And D will lie on the big circle by Thale's theorem

visual flume
#

wait what this is what google showed

civic rock
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yep

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and if you look at OCBA, you see the opposite angles add up to 180°

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so it is a cyclic quad

upper karma
#

Hhmm... my memory messed up avain

civic rock
#

so Ptolemy is applicable here

junior tiger
visual flume
#

ohhhh

civic rock
#

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

visual flume
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ohhhhhh

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i see

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tysm!

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i was trying to do it with inscribed angles all the time lol

junior tiger
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also if it is a problem related to sum of opposing angles in a quadri then pitots theorem is the solution

upper karma
#

I see.

civic rock
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anyways

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wait I found an easy way without Ptolemy

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CA = CE = 5

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then EO * EA = EC * EB
or 2R^2 = 5(5+3)
-> R = 2√5

upper karma
civic rock
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sorta

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you can see ∆EOC and ∆EBA being similar

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if we don't want to bring any cyclic quad shenanigans here

upper karma
hollow finch
#

chat im going into geometry next year is it easier than algebra 🙏

round beacon
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but for others idk

hollow finch
#

alright

shut pebble
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"Use your straightedge and compass to construct a triangle, square, pentagon, hexagon, and heptagon. How many steps did each take?" i'm stuck

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(regular)

civic rock
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Impossible for heptagon

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do you have an idea for a triangle?

shut pebble
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yes i did the first 4

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i was stuck on heptagon

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thanks

maiden brook
#

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

shut pebble
#

i know

maiden brook
#

ah

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cool

fresh birch
#

XD

analog maple
#

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!

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In fact the angle is wrong, because I'm calculating the difference between CA and H, but idk how we can calculate te angle

knotty quiver
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it's hard to differentiate your H and A handwriting

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also why not just use c for hypotenuse since it's the variable for it instead of H

analog maple
#

It's better like that?

west narwhal
#

Yes, I think so.

signal karma
#

a^2=b^2+c^2-2bccosa

analog maple
#

¿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

weary haven
#

Is there a special term for an angle θ that are defined such that it is defined for all real numbers θ

grave pond
#

What?

weary haven
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I mean

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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)

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unlike in elementary mathematics where angles are just defined to be not less than 0° and not greater than 360°

obsidian harness
#

when we say angle, we mean that the angle can be any real number

weary haven
#

oh

grave pond
#

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.

obsidian harness
#

yeah we don't really need a specific name

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it's pretty clear when a trig context will differ from a Euclidean geometry or an angle between two planes context

grave pond
#

It's good to be aware of these implicit differences in convention, despite the lack of generally understood terse words for stating them.

warped sail
#

I am gonna loose it

grave pond
#

Hint: Lots of ||central angle theorem||. All five points ||lie on the circumcircle of the square||.

warped sail
grave pond
#

Do you know the central angle theorem?

warped sail
#

yea but i cant see any of it here

grave pond
#

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.

warped sail
#

is that what you mean ?

grave pond
#

Yes.

warped sail
#

oh. yea i get it now

grave pond
#

It doesn't look very circular, but then again the square doesn't look very square to begin with ...

warped sail
#

I drew that myself so its not perfect

#

Thanks for your help btw

grave pond
#

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.

warped sail
#

the rest is easy, I just didnt see that inscribed angle

obsidian harness
#

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

warped sail
#

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

obsidian harness
#

I know just re-explaining why exactly you can draw a circle through all these points

warped sail
#

oh, ok thanks !

grave pond
#

(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°).

honest pumice
#

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?

silent plank
#

you are wrong

#

the question says that

x is the length of the side perpendicular to the river

honest pumice
#

ahhh, my bad

silent plank
#

you have the wrong location of x in your diagram

honest pumice
#

i assumed it was parallel, lol

#

thank god i'm reviewing my knowdledge of calculus before taking the real analysis course

honest pumice
#

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?

silent plank
#

you double counted the circles

honest pumice
#

don't i need two circles to make a cylinder?

silent plank
#

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)

honest pumice
#

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

cedar mist
#

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.

short osprey
cedar mist
#

Man, I just realized that I posted the wrong problem, already got the answer SEC^2(theta)

#

Thank you so much for helping!

short osprey
#

no worries

mystic umbra
#

8 pts is a bit much for a two to three line solution, but it could be just mecatglasses

cedar mist
#

I dont understand how you know so much, when you have such little context.

mystic umbra
#

w-what sully

#

?

short lynx
#

how do u find the coordinates of point k

grave pond
#

It asks for approximate coordinates, so you're just supposed to eyeball it using the grid lines.

short lynx
#

the x and y int right?

grave pond
#

They shouldn't be integers, if that’s what you're asking.

short lynx
#

ye so how am i suppose to find the decimals

#

do i js guess?

grave pond
#

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.

short lynx
#

Ok

cedar mist
#

Cos = x

Sin = y

#

You can plug them into your calculator for the approximate values

#

(-0.866,0.5)

obsidian harness
cedar mist
#

Sorry, ill stop now

obsidian harness
#

no need to apologise btw

cedar mist
#

I know, I want to help but don't want to give inaccurate info, so I kept sending before I checked, lmao.

short lynx
#

Oh

grave pond
short lynx
#

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

short lynx
#

it would be like (-0.8,0.5)

#

idk why its rounded to 3 decimal places

#

-0.866

grave pond
#

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.

short lynx
#

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?

grave pond
#

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.

short lynx
#

oh alright

grave pond
#

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.

short lynx
#

ohhh i get it

grave pond
#

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.

swift ibex
#

Can anyone help me understand how to apply trigonometry formulas while solving problems?

#

Anyone?

somber coyoteBOT
worthy eagle
#

@swift ibex u mean these?

swift ibex
#

Hii sorry for replying late

swift ibex
worthy eagle
#

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

swift ibex
#

Okay

#

Actually I did some of trigonometry but as lack of practice I forgot how to solve

worthy eagle
# somber coyote

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

cedar mist
worthy eagle
# somber coyote

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

worthy eagle
# short lynx how do u find the coordinates of point k

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

grave pond
swift ibex
#

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

cedar mist
worthy eagle
#

oh u did some work let me check

swift ibex
#

I'm glad I could solve one

#

I can solve this but some struggling with harder ones

worthy eagle
#

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

grave pond
#

I think he meant AB, BC, AC -- he has named the corners of the right triangle A, B, and C.

worthy eagle
#

oh

grave pond
#

(Where B is the right angle, and C is where we measure the varying angle).

worthy eagle
#

ok

grave pond
#

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).

worthy eagle
#

oh units

worthy eagle
#

sry for ping(tropo), mb

swift ibex
swift ibex
#

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

worthy eagle
#

do you remember the values of sin45°, tan60°...?

#

@swift ibex

swift ibex
#

Yep

worthy eagle
#

then just write their values there and then solve for x

#

it will become a linear equation of form
ax+b=0

swift ibex
hollow pawn
#

who can tutor me basics of trigo

#

Dm

grand condor
#

can anyone take a look of this problem, i already solved it but i'm still looking for better and simpler solution.

worthy eagle
grand condor
#

ok hold on

#

honestly, it's not that easy

grand condor
upper karma
somber coyoteBOT
worthy eagle
#

this was one more way to do it but both ways look equally time taking

grand condor
#

what about problem2

#

the first one is actually easier to handle

pale linden
#

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?

visual flume
#

help pls

#

im cooked

#

i got angle bad is 45 😭

#

tryna use angle chasing to solve for x (which is dp probably)

civic rock
visual flume
#

uhhhhhhhhhh
UHHHHHH
UHMMMMMMMMMMMMMM
ERMMMMMMMMMMMMMMMMMMMMMMM
theyre similar?

#

idk

#

im tryna use cyclic quadrilaterals to make abpc

civic rock
#

why are they similar then?

visual flume
#

thtas how i got bad is 45 😭

visual flume
#

dang it my pens broken

civic rock
#

what about angles ABD and APC?

visual flume
#

hold on imma try to fix my pen 😭

pale linden
#

yo we left angles in 2024

visual flume
#

ok finally fixe dmy pen

pale linden
civic rock
#

dell

pale linden
#

it’s not what im initially trying to solve but I think that should be easier?

civic rock
pale linden
#

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

civic rock
#

?

#

!xy

lime crownBOT
#

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.

pale linden
#

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

visual flume
#

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 ✅ 😀 catthumbsup or ❌ 😡 👎

fresh birch
fresh birch
# grand condor honestly, it's not that easy

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

short lynx
#

is cos always x and sin always y?

short lynx
fresh birch
#

sorry?

#

I didn't understand what you mean

short lynx
#

like would you find a similar question like that on the SAT math section?

#

oh wait nvm

#

its alr

fresh birch
#

:V

civic rock
visual flume
#

yipeee

fresh birch
cedar mist
#

Mathster*

fresh birch
#

jajajaja

tender leaf
#

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 🙂

upper karma
#

I don't know.

#

What??

civic rock
#

think of illuminati every time a triangle appears KEK

upper karma
#

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 🤞

grand condor
#

can anyone help me on the problem,pls, finding the maximum of y

upper echo
obsidian harness
#

but yes the way above is particularly neat

steep granite
#

can someone explain to me the sine sum and sine difference formula

#

i dont understand where cosine comes from

somber coyoteBOT
steep granite
#

why does cosine appear

worthy eagle
steep granite
#

im

#

in only alg 2

#

I never learned calc

worthy eagle
#

I can send you a derivation by diagram video, you will understand how cos came, wait a minute.

steep granite
#

so u can only understand where cosine comes from if u know derivatives?

worthy eagle
steep granite
#

theres a difference?

#

what is derivation?

#

oh

#

is derivation

#

still in calc

#

?

worthy eagle
#

"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

steep granite
#

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

worthy eagle
#

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.

maiden brook
#

No it doesn’t

#

taking the derivative is called differentiation not derivation

worthy eagle
#

opencry oh man, when he got confused with this. My brain also confused 'derivative' with 'derivation'

worthy eagle
dark sparrow
grave pond
#

Though, just to keep everyone on their toes, a "derivation" can also mean a linear operator satisfying f(ab) = f(a)b+af(b).

mossy mirage
#

yess sure

knotty quiver
#

terms confusement sad

fresh birch
warped pendant
#

how can i do this problem?

upper echo
warped pendant
#

okayy thanksss

zealous trout
#

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

worthy eagle
cinder ledge
#

||Try proving that PBC is congruent to RDA, then use CPCTC.||

#

What how to mark spoiler

worthy eagle
cinder ledge
#

Oh thanks

#

Also is the CPCTC part correct?

#

I am a bit rusty

worthy eagle
#

yes

cinder ledge
#

Ok thanks!

orchid tendon
#

anyone here read or is reading the book "Basic Mathematics" by Serge Lang

cerulean hearth
#

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.

lofty spear
#

@cinder ledge welcome to the mathcord c:

cinder ledge
#

Ty

night cape
#

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

knotty quiver
#

idk but i know u can form triangles in the unit circle

noble garden
#

yo guys help i cant beat this level on geometry dash

mystic umbra
little tendon
#

Hey guys, can someone help me with this question, greatly appreciated

lime crownBOT
# little tendon Hey guys, can someone help me with this question, greatly appreciated
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
keen shuttle
#

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

keen shuttle
keen shuttle
void drum
void drum
#

So its just multiplying

keen shuttle
void drum
keen shuttle
spark yacht
spark yacht
haughty root
#

I thought tanα=tan(β-π/4), then cosα=±cos(β-π/4).

#

while sinα+cosβ=√2cos(β-π/4).

#

oh no

haughty root
summer cradle
# keen shuttle Still couldn't solve the second one :/

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)

keen shuttle
#

Thanks y'all

little tendon
night cape
#

ohhhhhhh

night cape
knotty quiver
#

ya like what frances said

river sand
#

guys i have two exams for both geometry semesters tomorrow whar do i do 😭

knotty quiver
#

learn from your mistakes

simple vigil
#

how to do trigonometry easily i m in class 10

#

help me

#

i have problem with algebraic identity in trigo

silent plank
#

show the specific problem

#

many of those trig identity proofs involve the use of
conjugates and pythagorean trig identities

obsidian harness
lime crownBOT
simple vigil
#

i want to learn how to solve a question in trigo

#

like how to make a path

#

to convert ratios

silent plank
#

too vague, the topic is too broad
show specific questions

spiral lodge
simple vigil
#

overall i m stuck in remembering ratio

#

i know sin and cos

obsidian harness
simple vigil
#

cosec cot and sec

#

there name are very confusing

obsidian harness
#

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!

simple vigil
#

but there value like if somebody ask randomly

#

tell TAN 30

obsidian harness
#

well from the definition

#

you know that must equal sin(30)/cos(30)

simple vigil
#

then i have to think for a second

#

sin 30 = 1/2

obsidian harness
#

just trust

simple vigil
#

thanks bro

obsidian harness
#

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

simple vigil
#

i know this

obsidian harness
#

(cotangent is decreasing, the reverse order, but don't worry about that for now)

simple vigil
#

sin increase

#

cos decresde

obsidian harness
#

yep for first quadrant ofc

simple vigil
#

but i have a doubt in identity sinA=sin(180-A)

obsidian harness
simple vigil
obsidian harness
#

okay, so just to recap

simple vigil
#

is this for only sin or all ratio

obsidian harness
#

cos(theta) = x-coordinate
sin(theta) = y-coordinate

obsidian harness
#

but all ratios come from sin and cos anyways

simple vigil
#

but if i put A=180 this is false

#

bcz cos 180=-1

#

but in this formula it will be cos 0 = 1

obsidian harness
#

the correct one for cos is cos(-x) = cos(x)

simple vigil
#

okay

#

you helped me a bit

#

thanks

obsidian harness
simple vigil
#

i still have like 6-7 months before boards

obsidian harness
#

oh it's a bit dark

#

but yes, same height = same y-coord = same sin value

obsidian harness
#

you have plenty of time don't worry

simple vigil
#

but there is like 15 chapter in 10th class

obsidian harness
#

keep making progress on maths, also your other subjects ofc

simple vigil
#

my maths marks are not good or else in othere subject i m in top 3 students

obsidian harness
#

interesting

#

honestly you don't need to top every subject

simple vigil
#

no but i really like coding AI ML DL which require a lot of maths

obsidian harness
#

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

simple vigil
#

in coding i require like PnC

obsidian harness
#

honestly just try to do well enough to get into those uni programs

obsidian harness
simple vigil
#

honestly you know IIT

#

?

obsidian harness
#

but then there might be some coding scenario that is similar

obsidian harness
#

you aiming for JEE then?

simple vigil
#

not i want to tell i never thought of it

#

i want to go to

#

BITS PILANI

obsidian harness
#

oh BITS

#

@jaunty quail can you help me out with India specific stuff bhai

simple vigil
#

you know there is an institute in india which has only one subject

#

MATHS

#

and a student got a package of 60LPA

obsidian harness
#

crazy

simple vigil
#

yeah

#

its true

#

its in chennai

left mauve
#

Hello

left mauve
#

CS?

simple vigil
#

and i really like physics too

#

you know technical guruji?

left mauve
#

A bit

simple vigil
#

he is graduated from this college only

#

and many other

left mauve
#

Yeah well it's the top private eng college SparkleShrug

#

Getting in is not too easy

#

What grade are you in

simple vigil
#

10th

left mauve
left mauve
simple vigil
#

what about you

left mauve
#

I'm in uni

simple vigil
#

i think you are in 3rd year

left mauve
#

No, 1st year

simple vigil
left mauve
#

Yes

simple vigil
#

which college

left mauve
slender flint
#

BITS isn't in Chennai 😭

left mauve
simple vigil
#

its in GOA and PILANI (rajasthan)

left mauve
left mauve
slender flint
#

And Dubai

simple vigil
left mauve
simple vigil
#

bye guys let me go i have to do worksheet and work of triangles

obsidian harness
#

I'm not

polar otter
#

Hellooo

dire jackal
#

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

azure rivet
#

your point is true tbh

simple vigil
#

jee given by more than 12 lakhs students

#

meanwhile bitsat maybe 6-7 lakhs

left mauve
#

Uhh

#

Bits is a single college

#

Jee offers admission to multiple colleges

#

It evens out

dire jackal
#

if aim for iit, you have a better chance of geting into bits

#

aim for bits and you would prep less

pearl hinge
worthy eagle
# little tendon idk how the polygon even is whether its a regular polygon or some other type of ...

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

pearl hinge
crimson crescent
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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

solid radish
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Hi

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For the vertex form if it’s like x - 3 + 2

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Would the vertex be (3, 2)

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And if it was the opposite like x - +3 + 2 the vertex would be (-3, 2) right

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Sorry I posted it in the wrong channel

blazing ermine
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Can someone help me..

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It's physics..

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😓

dark sparrow
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otherwise you'll confuse everybody

spark yacht
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!da2a

lime crownBOT
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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/

spark yacht
simple vigil
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i have problem in such kind of question

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especially (viii) and (iv)

dire jackal
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yo is that 10th ncert by any chance

dire jackal
worthy eagle
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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)

simple vigil
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you are using identity (a+b)(a-b) =a^2-b^2

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?

worthy eagle
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yes

simple vigil
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what are you typing so long

dire jackal
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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

worthy eagle
dire jackal
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viii is pretty simple just expand the square

worthy eagle
dire jackal
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ohh ok

dire jackal
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things were so much simpler in 10th

worthy eagle
dire jackal
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hmm ok

simple vigil
dire jackal
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true it wasnt that easy when i first did it

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just do some practice and youll start to see certian patterns

simple vigil
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no like in vii part

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i have a solution to divide all by sin A

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both numerator and denominator

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first we will take common sin from numerator and cos from denominator

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then divide

dire jackal
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instead of dividing take sin common from numerator and cos from denominator and keep it as tanA

simple vigil
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we can expand this 1-cos^2 theta

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should i share what i have done?

dire jackal
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ye

simple vigil
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1-2 steps are skipped

dire jackal
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i mean yeah ur done its right

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why are you asking it then

simple vigil
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no like i found it difficult

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i took approx 10 min thinking what to do

dire jackal
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ohh damn

simple vigil
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i can't afford this much time on a question of 2-3 marks in boards