#geometry-and-trigonometry
1 messages · Page 83 of 1
Definitely not with elementary functions yea but wolframs answer makes me doubt if it is even solvable with non elementary ones
yea it was probably done analytically
Ig youre given the first result and you have to show the second one
Mmmm
yea but i don't think one follows from the other...
,w sinx + cosx = sqrt(2) sinx
huh?
💀 i just subbed the solution to the given equation in what we have to prove
Unless wolframs tripping hard then yea it does follow from that one way or the other
cos(theta)+sin(theta) = sqrt(2) sin(theta)
cos(theta) = (sqrt(2)-1) sin(theta)
sec(theta) = (sqrt(2) + 1) sin(theta)
sec(theta) = 2sqrt(2) sin(theta)
(sqrt(2)+1) sin(theta) = 2sqrt(2) sin(theta)
sqrt(2) + 1 = 2sqrt(2)
sqrt(2) = 1

um
ignore me
LOL
Sec theta = (sqrt(2) +1) / sin theta
yea 
Mmm
but then
csc^2(theta) = 2sqrt(2)/( sqrt(2)+1) ?
sin^2(theta) i mean
bro im trippy rn LOL
Mahn what are we even doing just weirstrass the first eqn thats given to us
And then get tan(theta/2)
And use that to prove the second eqn
Idk the elementary method
But this works
You were right when you have csc theta xD
i was?
no 😭
Listen just apply the weirstrass and its easy
Google sin(x) half angle identity in terms of tan(x/2)
And same for cos(x)
Then solve
you just did the same thing... 
I know I just followed your thing and ended up in the same place lol
I don't think half angles are allowed in my level i don't even know what they are sadly
What all is allowed?
i'm not getting anywhere 
I think there might have been a mistake no way they gon give us this hard stuff I'm in secondary school
From the given relation you cant get to a eqn in terms of sin and sec
Obv
Like jjst by algebra i meant
boutta throw hands
lol I though this was easy at first bout to start crying now
I mean its not tough yourr tools are restrictted that is the main issue
Is it even possible with the restricted tools I have?
Id be suprised if it even was
I think Using 3 perpendicular mirrors a light ray with an incident angle of 55° reflects back in the opposite direction, keeping the final incident and reflected angles at 55°.
Just draw the diagrans and angle chasing
The que is ambiguous tho? Does it want us to give it the total number of mirrors (including the original one) or just how many extras we used
I did it guys (I think) can you see if it's correct and I know I have horrendous handwriting
@faint pasture
@trail tendon
Cool
It is all correct from what i can see
Aight thanks for the help
that's impossible if you don't know anything about the radius
use the circle theorem that the angle at the centre is 2A
then split the isosceles triangle into two congruent right triangles
you get $2R \sin A$
south, just south
Proof of "a over sinA equals 2R"
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Wouldn't this mean that, since r in unit circle is 1, then a = 2sinA?
yeah
yep, it is simple just write the left side as sin(pi/2-t)+sin(t) and use sum of sines.
Suppose a cube has side lengths of a. What is the area of the region of points that are closer to the center than any one of the vertices?
This problem got a crazy solution and it was in an anime
Its formed by inetersections of mid-planes between the center and a vertices. So we get 8 faces. I guess its an octahedron with side 3a/sqrt(8).
Not quite
why not?
The mid points of those lines are good but it's not an octahedron and there's a much more elegant way
If you take the whole solid whose parts are outside of the cube it should be octahedron
for some reason you have taken only those points which are inside the cube
so, yes, if you cut out only the part inside the cube you will get the solid on you figure
never mind. the problem and its solution is clear to me.
Like making more points around the cube?
I mean, an equation of the midplane is easy: you take a vector from center to vertex: say (1,1,1) and you immediately get an equation (x-1/2)+(y-1/2)+(z-1/2)=0 And the same with two more non-parallel planes. So, we solve a system of 3 linear equations and find coordinates of just one vertice in that octahedron. The rest is easy because of symmetry.
And for cube centered at O with vertices like (1,1,1), (1,-1,1) we get vertices of the octahedron like (3/2, 0, 0). Just exactly as seen in the figure. So the side of the triangle is 3a/sqrt(8).
https://www.youtube.com/watch?v=64ZjFXrFBqE&t=161s&ab_channel=Phanimations Skip to 1:15 for the problem and from there watch and you'll see two solutions. One of them is basically bash, and the other one is the one
This is a stupid little scene I've had stuck in my head for years, so for anyone who watched it and was completely confused here ya go! Or, if you haven't seen Assasination Classroom, go watch it!
Music
NCS Chill Music
Free Chill Lo-Fi Music (For YouTube Videos) - "Colorful Flowers" by @tokyowalker4038 🇯🇵
Mata Kimi Ni Aeru Hi (Assassination Cl...
That's not very nice
Yes
YOu can't whip this devious stuff out
What is it
Send a picture and then I will decide
oh hell no
Pretty please
I'm a freshman rn
Good enough
assination
lets assinate some peeps
Wait how did bro know
that aint your homework 
maybe...he watched it :O
Maybe I tried to solve it
no, could never be
I solved it
what you get
The intregal stuff basically
It connects
Source : don'ttrustmebro.com
Sometimes I’m glad I’m in foundation maths and still in secondary school cause what is this 🤣
Lol
Yh I just made that up lol
You do
We was told that we don’t need to learn it for our exams even though the last question was what is sin 30
Only higher tier does that
Is it non calc?
There is an easy way to do it tho
You just need to remember sin that's it
1/sqrt2 is bad
that's better
I picked the 1st one I saw
Who ever made that
So many are like that
Yeah
petualant
So for sin you just remember the degrees at the top
The put 0 1 2 3 4
Then root them
And divide by 2
Just use a calc (slang for calculator)
There are calc and non calc test
Yeah my maths calc is tmr
Gl
Uh
We have 1 non calc and 2 calc
Oh you do gcse
Yeah
I did that a year ago it was pretty calm
Ahh yeah I’m assuming u did higher then aha
I kinda flopped didn't get the grades I wanted
Yh
What did u get
8
That’s really good
Only 1 grade off
Why are you still up isn't it like 00:14
Good point
Idk tbh I’m just watching maths revision videos
Mostly on simultaneous equations
The thing is if you revise just before you sleep you won't remember much
3 or 2 unknowns
Yeah that’s very true
I get how to work out x and y it’s the part when you make them the same that gets me
Better thing to do is sleep early and wake up at like 2 or 3 and revise
Oh damn
that’s pretty bad
Start you revision Like a month or two before the test and you are set
Yeah I did kinda do that but I’ve been revising mostly stuff I already know like Pythagoras and angles and stuff
Stupid move
Yh
So what do u do at college
Is college a levels?
Yeah
Ah
Well
I do maths furthermaths Chem and physics
Yeah loads of different routes to take at college but A levels are the main ones
Wow
5 hours sleep lol
That is pretty bad
Mostly cause I leave my homework until the last day
I always do that
I wake up at 5 normally arrive to school at like 7.30
If I have homework mabye I wake up at 3-4
Bro just do it through the day 😭
Yh I do some at school
Fair enough
Our school has like study peroids instead of free peroids
So you can like do homework/revise
My school does stuff like that
Period 7s
Absolute pain
Bro what
It sounds stupid
When is that 530
Basically it’s another lesson and you revise for exams and stuff
My school days are very different from yours I’m guessing 🤣
My school starts at 8:20
We typically leave school at 2:45
Oh we leave at 3
And then for year 11s like myself if we have period 7s they are between half an hour to 50 minutes depending on the teacher
Mist I had was peroid 6 during gcse
Most*
People who didn't meet their target had to go for a 7th one
yeah that’s basically period 7 at my school
Peroid 6 was an hour
My period 6 used to be an hour
Isn't a peroid an hour
Oh ok
Well at my school it’s 50 minutes
And period 5 for some reason is 1 hour
Don’t ask why even I don’t know 🤣
We also had Saturday classes
Bro did u go my school 🤣
Prob not
Fair enough I might go this Saturday
Oh
Ngl foundation maths has ruined me in what I can do
I wanna do engineering
I can do it but I won’t be able to a uni
My friend moved up from foundation like a few months before the test
That’s what I’m trying to aim for
Only some unis look at gcse
I’m getting a maths tutor and everything lol
Mostly a levels and stuff
Yh...
Stupid question I know aha but I thought it cause u need good GCSEs to get into certain A levels
They like gaslight you too much at gcse
Yh
Depends on the school
Fair enough
If you get 6+ you are set
7+ grades even better
I would show you my gcse certificate if I had them rn I just got them earlier today
Yeah with foundation I can’t cause max u can get is a 5 and the grade boundaries for edexcel are ridiculously high
Yh
Yh
It's in my files I'm too tired to get them
Fair enough
I can tell you off the top of my head what I got if u like
Can do
My grades aren't like crazy
I got 6 for physics, bio, French, business, both English
I got 7 in chem
I got 8 in maths, furthermaths , re and geography
That's it I think
Why do u do so many GCSEs
Ahh
And furthermaths was optional
Ngl it was way easier than the actual maths higher last year
how 🤣
The test I mean
Ah
It easy too
You should look at a past paper they are doable after you learn a few things
For someone who got a grade 8 it probably was easy
Yeah for these exams there mocks and old exam papers and I’ve found them on maths genie and Ive predicted which paper it’s gonna be
Eh I only revised for it the day before the test
But do you learn how to do them
Yeah what I normally do is I watch a video of a guy explaining it and if I don’t get a topic I try and rewatch if not I got on for example maths genie or dr frost and find the type of questions I don’t get from the exam and attempt them
I did that today and I did meh
Mabye lives streams may help
Yeah I’ve been watching some on TikTok
It’s crazy I’ve been revising purely maths for the mocks aha
Ah ok
Might not be a good idea
What subjects do u d
No mocks are just as important
I do history Re stats and engineering
Ik they send these to colleges
English?
Oh I also somehow got destination for that gcse speaking thing
I just waffled
I thought I was getting a merit
K good night
the question:
Write the corresponding triangle congruence theorem (SSS, SAS, ASA, AAS) and complete the congruence statement
i wrote " triangle STA is congruent to triangle RTA becaus eof the AAS postulate"
she then marked my paper with
Angle STA, and Angle RAT "Do you have 2 sides"
basically what it looked like
You have:
- ST congruent to RA
- Angle STA congruent to angle TAR
- Side TA is congruent to itself
Since you have a two pairs of congruent sides and the pair of angles included b/w said sides, it should be SAS.
thank you 🙏
wait so
would i do
triangle(STA) ≅ triangle(RTA) because SAS
or angle(STA) ≅ angle(RAT)
the order of the letters should match up w/ the congruent parts
because sas
ex. the angles at T and A are congruent, so those should match up in your names
$\triangle STA \cong \triangle RAT$ is one way to write it
Civil Service Pigeon
there's 5 other ways though so 
ight
thanks
By reading some messages I come to conclusion, that I'm so fucked up in school
What de hell I was thinking to go into high school

isn't it kind of mandatory...
don't think this needs a whole forum post, just going to ask; Trigonometry, unit circle, yeah? am I right in thinking every point on the circle's x is the cos to that angle/y is the sin to that angle?
yes, this is the unit circle definition
unit circle, as in the hypotenuse has to be 1 for this to work
otherwise it will be $(x, y) = (r \cos \theta, r \sin \theta)$
awesome, that's all I needed
south, just south
np!
ah so let s = side length of the red square
since the side length of the squares that make up the cross = 1
ye but i dont know where to go from there
then by Pythagoras we observe $s = \sqrt{3^2 + 1^2} = \sqrt{10}$ hmmm
southlander!
ah so that must mean that we have a pair of similar right triangles
southlander!
it follows that the short side = 1/3
and the hypotenuse of the small triangle = sqrt(10)/3
this is enough information to find the perimeter of the blue pieces
also note that 1 - short side = 1 - 1/3 = 2/3 appears multiple times
no, this length is 1
the squares have side length 1
oh yeah wait nvm
also I see 4 * sqrt(10)/3 in there
since it's the perimeter not the area I think you can't join up the three pieces btw
that works for the area ofc
i think i get it
ill have a look again tysmmm
np!!
Result:
15.549703546891
ah so it might be easier to think about it if you join the 3 blue pieces together, which has a perimeter of 3 * 4 = 12
then you have to add on the 4 edges which each have length sqrt(10)/3
,calc 12 + sqrt(10)/3 * 4
Result:
16.216370213558
@hidden willow
does anyone know a synthetic proof of existence of isogonal conjugates? (so no trig ceva stuff)
want to torture yourself ?? Have some fun dealing with some trigonometry problems
|| translate the question from french to english ||

Crazy ritangle
the question says it's made from squares actually
nice problem
ok sry ill delete my message
nice if you know your stuff
$\sec^2 \theta - \tan^2 \theta = 1 \implies \sec \theta + \tan \theta = 1/x$
southlander!
should be clear what to do from here
This is wht i did
yeah I think the other question with tan and sin is harder
since it gives you a choice I'd just do the easier question, haha
yea fr
This is wht I did for or
Question
which grade question u guess it would be?
I'd say 11th
ah nice
you are which level?
uni
oh I can't say but I study in Australia
oh srry
nice
which course u took?
im planning to take engineering
I switched from maths to sociology
but that itself is a vast field
I see
so u studied in australian curriculum?
yeah
nice
CBSE is rough
purely theoretical till 10th
like actually
i can't do a hydrogen pop test
oh lmao sciences
or study refractio thru glass prism
oh for us stream is only at 11th
so we have to study science math and sst all the way till 10th
yea they did
periodic classification of elements
cause now they'll shove all the info into 11th instead
yeaa
so I think making 9th and 10th a bit more rigorous is good
if it makes 11th and 12th more manageable
actually it is rigourous enough
true
we have board in like 2 months 😭
*boards
bcs this i didnt open discord for a year
like discord is literally dying
I had a trig test yesterday… I studied heavily the week prior but when I got to the big questions I blanked on part of the formula
Tan ( x) side/side
Forgot what x was and where to find it
Teach said there would be a retake but I dunno how the scoring will work. Hopefully I can raise my grade
they should introduce analysis in 9th, the lack of rigor in calc is quite concerning 
when you realize math gets easier and easier
where you get this idea from 
....💀 harder if you have a weak foundation, but in advanced topics its tricky
Like quantum mathematics as an example
thats physics 
You study it in mathematics to use it in physics its not physics
Quantum mechanics is physics
oh i thought you said mechanics LOL
Prove That A F > D B
Btw F is the one in the red circle
Split AF into FS and AS
are there anything else?
when you draw that line it gets proven, since in a right triangle the longest line is always hypotenuse
is 3pi/2 considered a solution for tan(x) + sec(x) = 2cos(x) or no
like desmos says yes, but undefined =/= 0 though
nope, tan(3pi/2) and sec(3pi/2) are undefined.
but like if i take the limit it does indeed say its equal
yes the limits are equal. But you cannot plug in x=3pi/2 directly into this equation. It has no sense.
mmm
thanks
Find the apothem and the area of the given regular hexagon with radius of 3 cm. Draw the figure using the exact measurement of the given radius.
How do i find it with only the radius given? What i know ks the radius+ midpoint of a side= the apothem. But i only have i given PLS HELPPPP
Radius + midpoint of a side?
Length + point
Uh
What
Yo can anyone tell me how to do approach in complex problems like of advanced level
can anyone explain this formula? what is m and where does this formula come from
@frosty rose It is like point slope form as far i have read
Brung that x thing to y and u are left with m
what is m?
These are various ways in which u can write an eqn for a line
If you are new to cood
"complex problems like of advanced level" 
Love it that y=x intersects the unit circle at irrational points, but when u shift it one unit to the left – it intersects only rationals
(yes, I was lazy to do it by hand lol)
There is also a quick way to find the equation from a tangent to a circle if you have the equation of the circle and the coordinates of intersection:
the lets say the equation of thr cirle is x²+y²=64
Let's say the point intersected is(a,b)
x²+y²=r² is the same as xx+yy=r²
You sub in the x and y values so the equation of the tangent would be ax+by=64
This also works if the equation is something like this (x-1)²+(y+2)²=16 and let's say the point of intersection is (c,d)
It would be (x-1)(x-1)+(y+2)(y+2)=16
you then plug in the x and y coords and you get (c-1)(x-1)+(d+2)(y+2)=16 this would be easier to expand with actual values, try it see if it works out
can somebody explain how this is correct
what all should i study for 10th grade geometry
i will try it in class today and see how it checks out, thanks!
You can prove that <5 + <6 = <1. The proof goes as follows:
We know that <1 + <4 = 180, so <1 = 180 - <4.
But <4 = 180 - (<5 + <6) since <4, <5, and <6 are the angles of the triangle WUV.
Now, replace <4 = 180 - (<5 + <6) in <1 = 180 - <4; this will give:
<1 = 180 - (180-(<5+<6)) = 180 - 180 + <5 + <6
Thus. <1 = <5 + <6.
Now... since <5 + <6 = <1, then both <5 and <6 must be less that <1.
Think about it in that way: 4 + 5 = 9, both 4 and 5 should be less than 9. In general, if x + y = z where x, y, and z are positive, then x and y are less than z.
How do we prove the statement "If two lines are perpendicular then the product of their gradients is -1" ? i forgor
Dot product?
WLOG you have (a, b) and (kb, -ka)
WLOG?
Without loss of generality
Those two
Basically you want any two vectors whose dot product is 0
😅 im still lost
how can i shorten these statements and reasons?
Wasnt there a proof without this
Yea
Like we know angle between two line is
arctan((m1-m2)/(1+m1m2))
And if this is pi/2
Then 1+ m1m2 = 0
And m1m2 =-1
@upper karma
brb
you can also do this with just pythagorean theorem
$|BC| = \sqrt{m_2^2+1},;; |AB|=\sqrt{m_1^2+1}\implies (m_1-m_2)^2=m_2^2+1+m_1^2+1$
daniel
so rearranging gives the desired result
back
how?
look at what i posted
m1 and m2 are derivatives right?
how can they be lengths of sides?
they're the slopes of the lines
Well technically they are also the derivatives
because BD is 1, AD must be m_1 in order for the slope to be m_1, same for m_2
😭 the tilted axis made it look weird
which ones are the tangents again?
Can someone solve this for me? It’s beginner physics PLEASE
a cannon ball is launched off of a 28 m cliff. it lands 22 m away and it takes 5.5 seconds. what is impact velocity with angle
there aren't any tangents?
AB is perpendicular to BC
The horizontal velocity is 4 cuz 22/5.5
For vertical just use the second equation of motion
To get the initial vertical velocity
And then the first equation
To get the final velocity
I did all that and I think I got 32 m/s [7 degrees from the vertical]
Idk if it’s right
the tilted axis did confuse me
i get it now thanks
I so dont wanna do the calculations so you are on your own
i could not do proofing
that stuff is wack
Guys I'm stuck on something, can any line. intersect on any point on a line and it could be it's bisector?
technically if a line extends both sides infinitetly, then any point on the line could be a point of bisection right?
or is there some weird caveat?
i'm considering the length of expansion of the line given a point in time as the line extends at a constant rate
so one side of tge bisector could be like 3m and the other is 4m
but thats just a given point in time
as time resumes, the lengths will change
but im not smart so idk
like you have a given parameterized line and a given point, and you want a function that tells you the distance from the given point to any point on the line?
or idk what ur tryna do
well say the line extends infitely
but before it does
the given line on the sheet of paper
which demonstrated finite in length
has line that perpendicularly intersects it
but to the observer it doesn't bisect the finite line in half
so in the beginning
the line starts with unequal length sides
you know what nevermind
I'm thankful I got that out
cuz now I look poopy
doesn't matter if both directions have infinite length
any point on a line will be a point of bisection
As I was saying what math is happening here 10th grade or 11th grade
and I assume the people doing this is middle schoolers
oh same thing
well its still pre-uni
Well I did it last year too
Pre calc and geometry
oh
Your answer is the 1st part
Use pythagoras theorem
Since it's a square, DBC becomes a right triangle upon adding a diagonal
and since it's a square, the sides are equal
if the sides are x, then the diagonal, by pythagoras theorem will be:
x2 + x2 = DB2
2x2 = DB2
DB = x multiplied by square of 2
root of 2
which is in the 1st part
Pls help I've been solving for the past hour and I'm genuinely lost
what do you have to find?
The area of the rectangle minus the area of the 3 circles
The rectangle side is 4
Is it a square?
Ah yes it's a square
Nope its a rectangle
If it were a square I would've solved it hours ago
4(sqrt3 + 2) is the area of the rectangle then subtract area of circle which is just 3pi
are there any formulas for calculating the area of a regular polygon with side length and number of sides given
cus i can't find any online
Probably not
If there was then they would output something if you put in 1 as the amount of sides
Which doesn’t make sense
Idk
2nd one is 4
k
can someone do the trig part
start by writing the LHS of 4i in terms of sin and cos only
then use the Pythagorean identity
It is a rectangle. You can tell because the top of the bottom circle goes slightly above the bottoms of the top circles. As for finding the missing height, here's what to do. If you look carefully, you can see that if you draw lines from the center of each circle to the contact points of the other circles, you make an equilateral triangle. You can then cut the triangle in half for a right triangle to be formed, with a hypotenuse of length 2, and a short leg of length 1. You then do pythagorean theorem, to find the long legs length is sqrt(3). You also have to account for the upper radius of the top circles and the lower radius of the bottom circle. This ends up being 1+(sqrt(3))+1. This equals 2+sqrt(3), this being the height.
For the original question, you first multiply the height and width, being 4(2+sqrt(3))=8 + 4(sqrt(3))
You then subtract the area of the circles, adding up to 3pi:
8 + 4(sqrt(3)) - 3pi
That is your answer.
.
(I forgot to reply to the message)
If you're more of a visual learner, here's pictures:
While I was able to help with this, I am currently in algebra 1, so don't expect me to help here often.
U r a blessing from the lord above
You're welcome.
The first and last answers are correct. I will give an explanation shortly
Proof for the first answer
Another easier way to prove this, is by just multiplying the sides by sqrt(2) to see if that equals the length of the diagonal
Proof for the last answer
you have good maths skills for only knowing up to algebra 1
keep it up bud
keep the effort and the energy up!
yeah like some people are a right mess, I'm guessing many others in your class
damn
ah yeah you do cover that in alg 1 though
Ye
I'm also pretty good with i
And have a full on desmos account
can someone tell a nice book for synthetic geometry? (or will this go in book reccs)
can anyone teach me this
Looks like inconsistent data or not enough info
Yea id say inconsistent
Sum of all angles in a triangle = 180
150+120 + angle 2 = 180
Angle 2 = -90 degrees
Which doesnt make sense
What’s the formula for area of an irregular hexagon?
maybe the 150 and 120 are outside
i.e. the two red angles aren't the ones that are 150 and 120
Then it doesnt satisfy the isocelless triangle condituon
Actually wait
one is one side and the other is on the other
Yea it does
My bad
Still tho
Ambiguous
If you gonna mark the angle and put a value nezt to it
Thats not the marked angle
Yea thats ambiguous
yes
Find the polar coardinate of (3,3)
one of the many problems with geometry problems that don't define everything in words
I dont mind just figures but at least do it properly
@oblique pagoda
Hello
So uhhhh
My exercise is to derive the trigonometric theorems with the Euler relation
Everything on the top is…bullshit, don‘t bother with that because I think it was a mistake
I very feel like the result is just in front of my nose, but at the same time, I‘m not moving at all and wasting time
So it would be nice if you helped me out
I‘m not your GIRLFRIEND BROOO
LOL
Wtf
You should use that $e^{ix}\cdot e^{iy}=e^{i(x+y)}$
daniel
That is what I did
Sorry I didn't look at your work
Yes there is a missing i
If you add the missing i and recalculate both sides, then equate real and imaginary parts, you get the result
BWHAHAAAHAHAHHAA
XDDDDDDDDDDDRIZZ
happens to everyone
You‘d be surprised how unconcentrated I can be
But yeah, you‘re right, thanks for the reminder
I can help u. Is it urgent? because I have to review trigonometry
,rotate
Couldn't find an attached image in the last 10 messages.
@lyric notch whatve you tried
how is k expressed in the format of x/k + d when the k in the function is a fraction
you divide by the fraction, so multiply by reciprocal
if k = 1/2 for ex, you have x/(1/2) = 2x
so I have the function 7sin(1/5x) + 2, that would mean it would be 5x + 0?
okay thanks for the help 
is there a way to solve this algebraically or should I graph it?
for a), the easiest thing you can do is find points a, and b where the function f is equal, so then the avg rate of change [f(b)-f(a)]/[b-a] = 0. like, you could find a point on the midline, and then add the period to it, and the function would be the same, so the avg rate of change is 0
then for b) you can go from the max to the min (or from the max to the middle), and for c) you can do the opposite
if thats confusing, this would be the visual of what im saying for each subquestion
hi
Bro this si brutally upsetting
Hi
can someone explain the steps for me?
do you know the dot product?
specifically, the two ways to compute it?
vw/|v||w|
problem is I cant figure out how to get |v| or |w|
it doesnt do a good job explaining
pythagorean theorem. if you draw the vector out on a coordinate plane you'll see what i mean
yep that did it
can someone help me with this one too
im supposed to convert it to 11cos270 and 11sin270 right
I can help you
i figured it out I was applying tan accidentally
Does anyone have any tips for Proofs?
feeling dumb posting this here but im super behind n I gotta lock in but would it make sense to say angle c is reflexive?
no, the reflexive property is that anything is equal to itself
what is true however is that angle ACB = angle DCE
cause vertically opposite angles have the same measure
The graphs of trigonometric functions always appear to be constituting of consecutive rapid growth and decay. Can I model a given interval using a logarithmic or exponential function? Just out of curiosity.
it is possible given a small enough interval of x
you should probably add together multiple exponential functions and logs though
here's a nice example for sin x
A clock has 6 hands instead of 3, each moving at a different speed. Here are the speed values for each hand:
1: Moves forward by $\frac{x}{12}$ degrees each minute
2: Moves forward by $x^2$ degrees each minute
3: Moves backward by $x$ degrees each minute
4: Moves forward by $\frac{x}{2}$ degrees each first minute and $2x$ degrees each second minute
5: Moves forward by $x$ degrees each minute
6: Moves backward by $\sqrt{x+y}$ degrees each five minutes
We know that two of these hands are the real minutes and hours hands, but that there is no seconds hand.
$y$ is a prime number that is a possible value for minutes in a clock, e.g.: 59 works, but not 61.
At the start, the clock shows midnight, which is the actual time. After a certain amount of time, 4 hands meet in one one spot, while the other 2 meet in another spot.
Question: What is the actual time?
⛊Alpha™
Where i can find all of the geometry formulas
doesn't exist
yeah
thankfully
Here's a better one
Logistic appeared to be the best option
Hey help me with this question please
Among all the rectangles with a perimeter of 20cm, determine the one with the maximum area
My result is 32cm
cause 4+4+4+8 =20cm perimeter
4*8 = 32cm²
That is not a rectangle though
4x4x4x8 is a quadrilateral but not a rectangle
It would look something like this which makes it a trapezoid
You can let w and l be width and length. The area is wl and 2w + 2l must equal 20 ( the perimeter ) so w + l = 10, so w = 10 - l. If you substitute this into the area, you get l(10 - l) or 10l - l^2
That is a quadratic that represents all l values that work and the y-value is area. If you graph it, it looks like this and you can see area is maximized at the peak
The length there is 5 and so the width is also 5. The maximum area with that perimeter is a 5cm by 5cm square, with an area of 25cm²
A circle line is drawn around the triangle. One angle of a triangle is 50 degrees. Calculate the narrow angle between the bisectors of the other two angles.
I have been stuck on this problem and I cant figure it out. Could someone please help me with it?
draw out a picture to start
Someone teach me trigonometry
send a screen shot
specifics?
Do you know what the law of sines is?
What is the problem then?
Yes I am aware what it is. What do you need help with, if you know what it is too? Do you want me to walk you through a question or?
You can solve for AC
Okay so there's your answer
Also it should actually be ~14
24 * sin(22 degrees)/sin(40 degrees)
How did you get 31.6
Did you type it in wrong
stop spamming this please
hi
<@&268886789983436800>
show smth specific
Are there any general tips or advice for writing proofs, specifically in a form with two columns. Statements and Reasons.
in 2 column proofs?
js remeber every little step needs writing so even if basically anybody with any level of math advanced beyond prealgebra can understand it you still have to write it
and dont stress about axioms when substituion can be aplied
The circles having radii A and B intersect orthogonally. The length of their common chord is:
@faint pasture
What was the condition for orthogonal intersections i forgot
2ff1 + 2gg1 = c+c1?
Actually wait
Im dumb we dont need that
niceee
,rotate
@faint pasture @wise pawn
These look oddly add and subtractable cuz of the symmetry but i tried that and it doesnt look like it took me anywhere
So i dont rrally have a clue
Wait a minute
Its just h1+h2= 0
Because of the family of curves thing
Ie all the intersection points of s1 and s2 also satisfy
S1 + Lambda S2 = 0
Lambda is just an arbitary constant
Doing that in here and subbing lambda = 1 gives us a circle as the curve if we consider only the x^2 and y^2 coefficients
And it would be a circle if coefficient of xy =0
I really need to revise circles
@lyric halo
i see
This identity holds, right?
$\sec(x+\pi\cdot k)=(-1)^k\cdot \sec(x)$
horizon2.0
Can someone help me to prove the angle ACD is equal to the angle HKB?
AK-simedian of angle BKC by defenition, so, BKH=AKC and AKC=DCA couse tangent
Is it only me or as a beginner, I find really easy to remember sin, cos, tan?
it's not only you
great, move onto more challenging stuff if you're ready
especially if you've already done a million right triangle find the side / angle problems, and it's making sense
what is the volume of the largest cylinder that can fit inside a closed rectangular box measuring 12 inches by 10 inches by 8 inches?
What’s the justification for why the cylinder can’t be along the space diagonal of the rectangular box? is it just because it intuitively feels like it leaves empty space?
Like relative to keeping it horizontally or vertically
bizarre
Hello can sb help me with this task pleas?
I would be very grateful for any tips because Im strugling with this task for very long time
Sorry its he right drawing to this task
This one is still not quite correct. M should be the midpoint of the longer arc BC and it looks like it is AC in your figure.
If it's still relevant.
First, show that triangles BJN and BAG are similar (J is an intersection of AN and BE). Then EJN is similar to EAG, and then deduce that GAEN is a cyclic quadrilateral. Then similarly for the other side HAFN is cyclic. The rest is easy.
from the angle sum identity
Im gonna go insane i believe its 4.5(root thing) 3/9 but idk
$\frac{\sqrt3}{2} = \frac{x}{9}$
southlander!
it's just 4.5 sqrt(3)
Heck yeah im right then!!
Thx!!!
:DDDD
Found another one im struggling with (sorry)
The adjacent should be x(square root thing) 3
I dont know how to get x in this
The opposite should be just x
$\frac{\sqrt3}{3} = \frac{x}{10}$
oh yes you need to rationalise
southlander!
I originally wrote 1/sqrt(3) but that's equal to sqrt(3)/3 by rationalisation
$\frac{1}{\sqrt3} \frac{\sqrt3}{\sqrt3} = \frac{\sqrt3}{3}$
southlander!
How to show Beta = 2 * alpha
so far, I know Beta = gamma + alpha
and Gamma = delta
are the sun rays parallel to the x-axis?
yes
then delta = alpha by parallel lines
is that a theorem?
paris pamfilos' lectures on euclidian geometry is ass
Just read EGMO
i dont watch elmo
Euclidean geometry in mathematical olympiads
although my statement was one of general acknowledgement
i will consider your suggestion
i wish that book put a bit more effort into explaining things
i think aops does it better but its a lower level
HELP
My teacher sucks at teaching and I’m failing the class with a FINAL of 68
I’ve never failed so bad before
Guys help me figure this out: determine cos(2pi/3) using the ratio 30-60-90
2pi/3 is 30°
okay thanks!
Do you have ur special angles memorized lol
yesnt
assume there exists a triangle XYZ such that XY = 4, XZ = 8, and YZ <= 4
show this breaks the triangle inequality
hence by contradiction, YZ > 4
oh well YZ = 4 is a degenerate triangle, so the statement you have to prove is not technically correct
Does anyone know what this rule is called (if it has a name)
this follows by similar triangles
$\frac{a}{b + c} = \frac{b}{a}$, (short leg) / (hypotenuse) constant
south
$\frac{e}{b + c} = \frac{c}{e}$, (long leg) / (hypotenuse) constant
south
$\frac{d}{c} = \frac{b}{d}$, (short leg) / (long leg) constant
south
can someone give me a hint?
A circle is outscribed around the triangle ABC. Chords, from the middle of the arc AC to the middles of the arcs AB and BC, intersect sides [AB] and [BC] in the points D and E.
Prove that (DE) is parallel to (AC) and passes through the centre of the inscribed circle.
Ik the angle bisector thing(that it passes through middle of arc)
idk how to approach
@obsidian harnesstysm
no worries!!
can someone here explain trigonometry real quick?
This video tutorial provides a basic intro into trigonometry. It explains how to evaluate trigonometric functions like sin, cos, and tan using soh cah toa and right triangle trigonometry. It explains how to use reference angles and coterminal angles to evaluate trig functions such as sec, csc, and cot.
Trigonometry - Free Formula Sheet: ...
if you have any questions about the videos you can ask here
Too late now i failed the test ive worked so hard to prep for (it was mainly on cos and sin, this was in the study guide)
<@&268886789983436800>
please don't advertise this here.
the server isn't really for advertising your paid tutoring services.
hi guys so we did a test recently and I got a different answer then my friend, he got 9 while I got 3.9 for X. I have a feeling I did something wrong can anyone correct me?
x= 9
use the side lengths
simply the porpotions
so do 77/21 = 11x +11/30
and then solve for x
77/21 x 30 = 110
110 - 11 = 99
11x = 99
x = 99/11
x= 9
@twilit girder
np
quick question though, how comes its 77/21 and 11x + 11/30 rather then what I wrote?
u did 11x + 11 /21
yeah
i think you kinda got the picture right in your head but you executed it wrong
its because that wasnt the porportional adjacent side
with ur image it kinda looks similar so i can see why u got confused
in the question the triangle was the opposite way so I switched it, my friend thinks that could of caused the mistake
yh
u confused it around
becuase if they are porportional means it has the same ratio to each other
so u divide it by each other to find x since they are similar
if a and b are proportional a/b is the same value
if u understand
np
Can someone help me with this question? Im not sure if the solution takes the form of a ± or not
sin(arcTan(1/x))
yo what grade are u in
10
I am in grsde 9 and I am working on that lol
any tips
It's pretty complicated for me
oh trigonometry?
yes