#geometry-and-trigonometry
1 messages · Page 208 of 1
area is the inside right.
...yes
how the heck do we count the inside of a square?- im sorry im stupid and I am extremely bad at math...
a square is just about the easiest shape to compute the area of...
all area is based off of squares and rectangles
if the side length of a square is $s$, then its area is $s \cdot s$, or $s^2$.
Ann:
this is the reason we call things raised to the second power "squared"!

🇫
blue triangle minus purple triangle
ah thanks
subtractive area calculations like this are pretty useful a lot of the time
whats the difference between a circle and its circumference
there isnt one right
a circle is the locus some distance from a set point, not the figure bounded by it becuase thats a disc?

A circle is a shape
the circumference is the length along the outside of the circle
a circle is formally a line though
More like a line is a circle
?
I'd rather say a circle is a collection of points
You can consider a line as a circle with radius infinty
well yeah thats what i said before
a locus some distance from a set point
and technically a line segment or well in this case a curve is also a collection of points
my question was is there an actual distinction between a circle and circumference
The locus of the points with a constant distance to a given point
Well yeah
The circle is a geometrical object
Its circumfrence is a number
Perimeter
oh alright so the circumference is the length itself
What's the difference between surface and area
Same thing
Area=measure of surface
Surface is geometric object
Area is measure of the surface
Circle is geometric object
Circumference is measure or the circle
I need help
well use the fact they are similar triangles to help you
^
Sorry D: I'm trying to find the rules but is kinda hard to find
no worries, just put your question here (or preferably in a question channel)
well nothing will undo the ping, so just ask it now lol
Okay ':D I'm sorry. I'm doing example B (it already done but I want to know how do they did it) and I want to know why the 16 went over -56
how do you isolate cos(R) then?
Yes
$-56\cos(R)=16$
⚡Amphy⚡:
Isolate cos(R) for me
I really you know how to...because how did you even get this far in geometry then without knowing algebra basics...
Long story...
isolate cos(R) please
Thank you very much! If I want to ask more questions, which channel should I use?
you can keep using this one then, since you already occupied it lol

Is this okay?
well no original triangle to reference
Sorry!!
I can show you the one on my notebook if it's better
But that's more exact
you are incorrect
you messed up here
580 - (576 * cos(21))
$580-(576\cdot \cos(21)) \neq 4\cdot\cos(21)$
⚡Amphy⚡:
yes, but you have to realize why you were not allowed to do what you initially did
Because 576 is connected to the cos21?
recall order of operations
PEMDAS
multiplication comes before addition or subtraction
so you have to multiply 576cos(21) first
then you can do the subtraction
then you take the square root of everything
Yes yes 

Now comes the hard ones, the ones the ones that got my class all messed up
lol hardly a challenge for us though
this will be easy to work through, but I'm not going to be the one doing most of the work, I just give pointers lol
give me a minute lots of stuff happening at once
Take your time :0
correct 

Have a nice night :)
how would i calculate the angle of a point in a plane compared to another point in a different coordinate in the same plane? like A(2;4) and B(3;7)
you mean like if there was a vector from (0,0) to A and a vector from (0,0) to B, what is the angle between them?
a line between A and B and the angle of that line
can you show picture of what you mean?
is there a tool for drawing a plane and points on it?
or do i have to go on ms paint
What have i done wrong here?
use desmos lol
The three circles have the same radius "r", the lines are paralel and circles are tangent
geogebra is good too
thanks
ok, imagine a line between those two points. i want to know how to calculate that line's angle based on A looking at B
angle that line makes with the x axis then right?
yeah
one way is to see that theta is equal to arctan(y/x)
so arctan(4/2) will give the angle
well perhaps no
hmmm
because then arctan(7/3) would be different
I should play with it geometrically then
"If the slope of a line is m then the angle is θ=arctan(m)"
looks like that's your answer, had to look it up lol
i'm gonna be honest. i'm bad with angles so i don't know how sin, cos, tan and arctan works
neither θ
theta is common notation for the angle
arctan means tangent inverse, arc[insert trig function] means inverse[of that trig function]

i need to be able to be good at trigonometry to be able to make 2d games but i just suck at it so much
i'm better with algebra
i don't understand cos, tan and sin
how did they appear, how are they calculated
why isn't sin(2) = sin(1) + sin(1)
more than we can explain over discord lol, you'll take a course on trig though and you'll learn it then
why would sin(2) be equal to 2sin(1)

in all honesty, khan academy has a good trigonometry course
Ok so i rlly need help with some trig h(x) = 3 sin(2x) sin(10x) basically i get the amplitude and the two periods of the functions individually but when multiplying 2 functions how exactly does it work how is the new period determined how is the new amplitude determined etc.
uh
well ok for starters this won't be a pure sinusoid
second you can rewrite it using a product to sum identity
yea i tried graphing it and got a period of pi/2 which i didnt understand how the two periods related to that value
$\sin(u) \sin(v) = \frac12[\cos(u-v) - \cos(u+v)]$
Ann:
so you get $h(x) = \frac32[\cos(8x) - \cos(12x)]$
Ann:
im a little bit confused about the period
because when graphing i observed a period of pi/2
indeed
cos(8x) has a period of pi/4 and cos(12x) has a period of pi/6
the "greatest common integer multiple" of these is pi/2
well... generally, yeah.
well it can't be greater than 3
because when graphing my valuse didnt go from 3 - -3
but to find the exact amplitude i'd differentiate the thing and find its extrema
it suffices to find them on [0, pi/2]
bc periodicity
ok
thx this helps alot
@dark sparrow sorry to bother but i just had one question how did you go from 1/2[cos(u-v) - cos(u+v)] to 3/2[cos(u-v) - cos(u+v)]?
huh what
your thing had 3 as a coefficient
so the coeffecient becomes the numerator
what
no
jeez
i just went from $3 \sin(10x)\sin(2x)$ to $3 \cdot \frac12 [\cos(8x) - \cos(12x)]$... don't overthink it
Ann:
oh i see sorry im very new to this type of trig as i am first semester year 11 thanks so much for the help
Whats the proof for the second one
For SAS:
OM = HG S
<O = <H A
Since the angle and side are connected and we need another connected side for SAS(i.e. angle included between two sides)
HJ=OK S
For ASA:
This time one side should be connected to the two angles. The only other connected angle to the given sides is<M and <O
So,
<M=<O
If by HL you means RHS,
KM=JG H
Hello, I'm studying trigonometry with unit cirlce and I don't understand why a cosine or a sine can be negative ? Isn't it a lenght divided by another length ? Sorry if it is the wrong place to ask this
it's signed length
it conveys information about direction
cos(x) and sin(x) are the coordinates of the point on the unit circle that you reach if you turn x radians around the origin in the counter-clockwise direction starting from the point (1, 0)
the x-coordinate of the red point is cos(x),
the y-coordinate of the red point is sin(x)
Thank you so much for this explanation !
can you guys help me out with this
If tan(x + y) = 33 and tan x = 3, find tan y.
there's a formula for tan(x+y)
you can find it by using formulas for cos(x+y) and sin(x+y)
you can find it by using formulas for cos(x+y) and sin(x+y)
I tried using that but I couldn't get anywhere
what did you try
tan(x+y)=(tanx +tany)/(1-(tanx)(tany))
Plug in the values of tanx and tan(x+y) to get tany
Easy way to think of it, area of base * height
area of the base is a quarter circle
Area of a quarter circle: $\frac{\pi \text{r}^{2}}{4}$
⚡Amphy⚡:
Base Area * Height = $\frac{\pi \text{r}^{2}}{4} \text{h}$
⚡Amphy⚡:
height is 10, but also check your area
you used the formula correctly? If you did then you got the right answer
no need to ask me if you followed the formula correctly
your answer was?
correct
for regular solids, to find the volume, just remember that it will be:
(Area of the Base) * (Height)
bruh
why didn't you just post there though?
are you familiar with the definitions of the six trig functions?
you will also need to solve for c first, how would you go about doing that then?
now take its square root and you have the length of c
you could just leave it as sqrt(149) if you wanted
ok
can anyone assist?
so sin= 7/squareroot(149
yes, just follow the definitions of the trig functions and you will get it right
what is the aim of the problem?
Trying to find the base and leg
Or two legs if that makes sense
are you familiar with sine and cosine?
@upper karma
Yes
you had question?
Yeah

sooo
i understand to do 6^2+ b^2 = c^2
but like how do i do that without have b or c
use the trig ratios to help you solve
you have an angle and an opposite side, what could you use to find c?
B and A but how
you can use a trig ratio, as I had already stated
I see what you want me to do but i dont know how to do it
65/25
what does that even represent?
Opposite and hypotenuse
Let's just start from the definition then.\ $\sin(A)=\frac{\text{opp.}}{\text{hyp.}}$
⚡Amphy⚡:
right? you know that is true
yeah
65
and what is the opposite side?
25
do what do we want to solve for?
2.6
I didn't say anything about numbers, I said what are we trying to solve for?
so that will be c
$\sin(65)=\frac{25}{c}$
⚡Amphy⚡:
solve this equation for c, and that will be the answer
27.5
correct
so now you can get b
@upper karma you had a question about the area of a regular polygon?
I got an email from my math teacher that said my previous answer which the paper said was incorrect is actually correct, so I'm sorry for bothering you
if I ever have further questions I'll ask
ok then lol
I am having trouble getting b is this right so far 36+b^2=756.25
you can also use a trig ratio as opposed to solving it with pythgorean thm
ok so i would do opposite/adjacent
what is that trig ratio called?
opposite/adjacent
it has a name
tan
tan(x)
ok
you take the tangent of something, tan on its own doesn't mean anything
it's a bad lazy habit to just write sin, cos, tan
oh right ok
because they are functions, not just words
so you should get used to writing sin(x), cos(x), and tan(x)
ok.... will it be then tan(x) = 6/b
x is what though?
25?
but that is correct, just put in the correct number for x
x is the angle
wait your answer for c is wrong
I was just going off the numbers you gave me, but like since when was 25 degrees the length of the opposite side?
65 is the opposite
opposite means opposite side...
the only place an angle will appear is in the x for the trig ratio, the rest of the number are lengths
I don't even know what you are trying to say there
because you used angle measures in place of length measurements
you will have to review the trig ratios then
yeah i see that now but idk what to do from there
are you guys talking about SOH CAH TOA
yes, but we are making our way through it
correct
I want to get c so i have to do ........ sin?
so how about you repost the screenshot and tell me all angles measures you have
and tell me what lengths we are given
ok, so we want c
yes
would it be 6/c
6/c equals what?
you have to say what it is equal to
that is very important
because 6/c is just some ratio, it has no meaning to me
sin(x)= 6/c
what is x then?
x would be 65
ok so write that all out and then solve
c = 6.6
so b is 7.56
show me how you got that answer then
b^2=7.56
you need to take the square root
because you have b^2, not b, and you want b
how do i take the square root out?
what?
something is being squared right now, so to taking its square root will undo that squaring
I guess, I can't do square roots in my head, but that sounds correct
c is right but b isn't
so then you messed up a bit somewhere or there is round off error
you can just use tan(x) to solve for b instead if you wanted
that should be more accurate
wait...how did you get 3.78?
I should have realized that was way off, but oh well 
square root does not mean divide by 2 if that was what you did
i just divided by half and crossed my fingers couldn't figure it
yes but like i don't understand how to get rid of it
you were attempting to get rid of a square, not a square root
to get rid of a square, you take the square root
ok thanks for helping and dealing with my stupidity
it's all part of the learning process, that's all, nothing stupid about it
Answer is right but how would ik it’s a right angle? @me
<@&286206848099549185>
@solar shale is that line labeled as "15" meant to be tangent to the circle
So if there is a tangent then it means 90 degree angle
a tangent is perpendicular to the radius drawn to the point of tangency.
Ah ok
(in the future, post your q, then ping helpers if you don't get any replies within 15 mins)
well what have you tried so far
no, you never "have to" do anything
o
don't think in terms of "do i have to do this"
ok
think in terms of "if i do this, what'll that give me?"
so my original equation is r=2sin(x)
I get how we wind up x^2+y^2-2y=0
I don't get how they complete the square of that to graph it? how can you complete the square with three terms
negative b over 2 a right? 2/2
x is already a completed square? because its the only x term?
oh ok
cool I see it now
my teacher wrote it like this though
(x+0)^2 + (y-1)^2 = 1
is there any reason to write x like that?
is x^2 wrong?
maybe to accentuate that 0 is the x coord of the center, but not for any other purpose
they want me to go from rectangular coords to polar. x^2 + y^2 = 9 I know x^2 + y^2 = r^2 so r = 3
how do I get the angle though?
if only it explicitly said it was a square, then that would make things easy lol
@cloud merlin not quite
it is a square
does this help?
there shouldn't be any square roots in the final answer lol
the answer for this is pretty easy to find lol
saying its "pretty easy" isnt exactly helping
although man, TAing would be a lot easier if so
thought he figured it out already
I'm thinking he knows what to do at this point though
look ill draw it out
did you get the answer though?
or you still thinking that it's going to be 3 m^2?
square root of 18 to the power of 2
can you simplify that?
here let me show you
$\sqrt{18}^2$
Namington:
i just want you to rewrite that in simpler form
yes, your work is correct
but your answer can be simpified
if we take the square root of something, and then square it, what are we left with?
i gtg ill be back later
Namington:
and then you need a unit of m^2
so, the area is 18m^2
that rule should intuitively make sense too: if x*x = some number
then the square root of that number is x
and x^2 = x*x = that original number
in other words, $\sqrt{18}^2 = \sqrt{18}\times\sqrt{18} = 18$
Namington:
since sqrt(18) is the number that, when multiplied by itself, gives 18.
To find the height of a pole, a surveyor uses a theodolite. The theodolite is 4 ft tall. The surveyor stands 140 feet away from the base of the pole. Then she measures the angle of elevation to the top of the pole to be 38o. What is the height of the pole? Round the answer to the nearest foot.
can somebody help me
well the height of the pole will be given by x+4, but then the question is what is x?
assumption: that is a right triangle
not explicitly given that it is a right angle but looks close enough so that works for me
anyways, we have an angle and a side given to us, and we want to find another side, what trig ratio will help us out?
trigonometric ratio, (sine, cosine, tangent, etc...)
where did you get that picture though? says angle of elevation is 38 but then there is 44?
then it seems like you added in 38 on your own?
oh i forgot about the 38
can you give me the correct graphic then
thats the picture
because 44 degrees was never given, but it's there
its in the picture
your statement says 38 degrees
yeah in the question does say that
then the picture puts the 38 on the hypotenuse as if it was a distance measurement
so I'm not very sure what is the correct angle to use
lets just use 38
ok so scrap the 44, and replace it with 38, that will change the answer of course
so sin 38 = 4/140 ?
4 ft
x is nowhere in that equation
4ft is not even part of the triangle we are looking at
what is the definition of sine?
sine of an angle is opposite/hypotenuse
how is 140 the hypotenuse? your picture clearly shows that 140 is a leg
but you are correct with your definition of sine though
just putting in the wrong thing
currently we don't have the length of the hypotenuse
perhaps we should try a different trig ratio
it said 38 was an angle measure
then how are we suppost to find the hypotenuse?
38 is impossible anyways given one side is 140
we don't need the hypotenuse, we can always use a different trig ratio, unless the only one you have been taught is sine
we have been taught* cos and tan but we today we used sin
what is the definition of tangent and cosine?
perhaps considering other trig functions will be useful because we see that sine is not going to help
cos = adjacent/hypotenuse and tan = opposite/adjecent
so out of the two only one does not need the hypotenuse
we have one of the legs and we want the other leg, so let's use..?
tan
let's use tan(x) because then we won't need the hypotenuse
so what would the equation be?
tan 38 = x/140 ?
no need to be doubtful when you literally followed the formula, you are going to be correct when you apply the formula properly
?
yes
need help?
yes
sure do you guys understand triganomatry
yes
i dont
dsghklf
ok wait a little
not a big math guy
can we please like
more into science
x=109.37998771
granted i've seen worse but
you know the definitions of the ratios though, we are just helping you to see which one to use
yeah
ok, so it said round to nearest foot, so please do that
109 ft
perfect, now the final step
the length of the pole is given by what?
look at the figure if you are unsure
what do you mean given by like the elavation?
they wanted the length of the pole, which is on the left side of the figure
so x
this is a strange picture, you sure this is straight from your book?
not from the book she send us a link to a google document
I'm pretty sure that the length of the pole is x+4
Look at the right
4 ft on the right
That acute angle
you need to add 4ft
Wait let me get my calculator
that is the answer, yes
The answer is
don't use 44 degrees
the problem gave a different angle measure
Just change the 44 to any other angle
Also this works with degrees so calculators have to be on degree mode
let's not make this problem any more confusing than the graphic already is by introducing a formula that uses two trig ratios
so the answer to that problem is 113 ft correct?
Idk I don’t have my calculator
given what you told me, yes
again that picture is the worse thing ever, because it has two angle measures and one is not even labeled properly, but we went off of what the problem said
but do you see why the height of the pole was x+4?
and not just x
we need a better picture to properly show you things lol, but you can see that it's not always hard and fast about what ratio to use
you take a look at what you are given and choose the ratio that utilizes the givens to find the unknown
i also have 1 more problem I did but I'm unsure if its correct if u could check it
hopefully that one has a better picture 
sin is the best like all the other trig functions dont need to exist
what?
tan64=x/7
x=14.35212689
x=14
wait i need so round to the nearest tenth so it would be x=14.4
that would overcomplicate things
still
why sine? it could have been equally just cosine then
what? um no, all of them are fairly easy to understand
you are correct nickk
I'm not sure about rounding; it's whatever your teacher wants
wait i need so round to the nearest tenth so it would be x=14.4
plus if you get rid of everything except sine, then the unit circle would not be nearly as nice
ok, with rounding, you are still correct
All trigs are easy tbh
thank you all very much for the help I understand this very much better
that is overly complicated
thats what people who dont understand say
then how does the unit circle look for you
what
that's why lol, once you realize the implications of this to the unit circle you will stop asserting that sine is the best
it is
its the simplest to understand
well maybe cos is also easy
but sin is just cool
sure, but it's not the end all be all
what does that mean
Now you ruined the simple identity of: $\sin^{2}(x)+\cos^{2}(x)=1$
like exact value?
yees
⚡Amphy⚡:
no shit
for this problem would i also have to use tan?
well what are you given?
overcomplicates things
stop please
the problem is just "Find the value of x, rounded to the nearest tenth."
we are working on something
even pi can easuly be calculated with sin
Two questions at the same time?
@sleek knot ping me in one of the question channels
Make sure its empty
no man, don't leave me to argue about ratios lol
well looks like he's gone....so let's continue
please stop, I have a question I am working on with someone
Well forget about that
we can argue after this question because its the last one
x is the hyp
I'll let wolf take the lead lol
the only thing for hard is, is just to choose the correct treg ratio
but i sort of understand now
stage is all yours
lmao it's fine if you wanna
no no, lol you're eager for it so be my guest, need to get back to work lol
alright so would it be tan?
Whats 32?
not sure its just there
anyone watch anime?
xD

one piece and stience gate are sick
also sorry if i distracted you of your work @Amphy⚡#0697
@cloud merlin Warning, don't spam here
nah I do this on my own time, you're good
thanks for the help again
Let's ignore 32 for now?
yeah lets do that
but anyways someone is attempting to help you, you should move into a help channel and lock it to keep spam away
We can either use the ratio 11/x or x/11
Right?
Because we have no idea about the other side
yeah x/11 because x is the hyp pretty sure
Yee
so tan 28 = x/11
lemme use a calculator real quick
here you go
thats all i needed thank you for the help
np
Want me to kick your banana, @plucky marlin ?
lol just kidding
xD all cool
have a great night (or morning wherever yall live at)
,w time India
wait the missing side was a hypotenuse
but hypotenuse is longest side and it's 5...? but a leg is 11...so that's an impossible triangle lol
some random ass 32 included because the teacher sucks at making graphics, but you guys solved for the opposite side lol
@sleek knot you found a side that you didn't need to lol. I think the graphic confused him
here's your chance to make it right lol, go for it lol
@sleek knot @sleek knot @sleek knot @sleek knot @sleek knot @sleek knot @sleek knot
I MADE A MISTEKKKKKKKKKKKKK
It's cos and not tan
ok ima do that thanks
why would you do that to yourself?
do what?
making it overly complicated for no reason lol
what is even being done there
you guys want me to explain them?
the third one is pretty basic but i can explain the sin and cos
i mean it's not even clear what you're going for there
can you post the original problem you were doing
$x = \frac{11}{\cos(28^\circ)}$
Ann:
which even appeared in your work
help, how do I solve this I dont seem to understand it even though it gives a hint
have you done what the hint tells you to do?
yeah I made a line that goes through B and D
okay
so this gives you two triangles
ABD and CBD
are you able to calculate the area of each?
BCD
the vertices of a triangle can be listed in whatever order unless you're making a statement about similarity, which i am not.
that's beside the point, anyway.
what if I say no?
then we're going to step back from the problem for a moment
but until you say yes or no, i'm not going anywhere.
well im 50/50 with that
what do you mean 50/50
my guess would be 1/2basinB
i can tell that you wrote sin*B there. that's inappropriate, because sin B is not the product of B and something called "sin".
(and it should be sin(B) anyway)
but that's beside the point
I dont care, I just want to know how to do it
ok, you've blurted out a formula. you should probably give it some context, such as describing what the variables in it represent and what its output is meant to be
that's the area of ABD, yes
are you able to calculate the area of the other triangle?
hmm
if you were able to do that for the first triangle, then you should also be able to do it for the second.
half * 6 * 6.76 * sin(C)
the what letters?
you should not be concerning yourself with sticking to one particular set of labels and attaching them to every triangle you see
well thats what ive been doing
you should instead understand visually what elements of your triangle the formula involves
i dont know
if it was something like ABD how would I state that
with the small labels
okay so look
the formula you know as 1/2 ab sin(C) involves two sides and the angle between them.
yes
the exact names of those sides and the angle DO NOT MATTER
and my point is you should not attach yourself to any particular names
so I could in between A and B i could put small a?
??
i don't know, would it?
no
- Requesting or offering the exchange of money for completing homework assignments is a bannable offense.(modifié)
<@&268886789983436800>
your problem, not ours
I think she isn't even if she is almost fluent in french
my french is at the level where i can shitpost to some extent but can't read real french literature for shit
most of french people can't read french litterature when it's old
maybe not "cant read"
but have difficulties to understand a lot of sentences
do you have any you could recommend me that isn't like that 😂
No I don't read a lot of books
And I don't think it exists x)
french writers love to use words that nobody uses in common life
maybe some books of Andrée Chedid because she's a recent writer
🤔
how do you solve this one? I know how to find area of a triangle but I’m not sure how to apply it
the area of the triangle is xy/2
just solve for x in terms of theta and y in terms of theta and then plug
its 4sin(theta) and 4cos(theta)
yeah divided by two
would be nice if I can get some advice on tis
it gives us 3 sides?
tell me, what shapes does heron's formula let you find the area of?
perimeter of something
i used it on a right angle triangle and got the right answer
how?
because there is a MUCH SIMPLER way to find the area of a RIGHT triangle.
what you did is the mathematical equivalent of using a sledgehammer to hammer a nail.
i made sure i was on the safe side
and my other point is that heron's formula is a formula that lets you find the area of a TRIANGLE. but QBCR is NOT a triangle.
QBCR is NOT a triangle and heron's formula applies ONLY to triangles.
we can turn it into a triangle cant we?
you don't need to turn it into anything
it is a trapezoid
go review your area formulas.
0.5 * ac sin(B)?
you CANNOT just blurt out formulae without saying WHAT THEY APPLY TO.
if you don't know what a formula applies to then you DO NOT KNOW THE FORMULA.
those are the formulas, no?
if you don't know what a formula applies to then you DO NOT KNOW THE FORMULA.
if you don't know what a formula applies to then you DO NOT KNOW THE FORMULA.
if you don't know what a formula applies to then you DO NOT KNOW THE FORMULA.
if you don't know what a formula applies to then all you know is a jumble of symbols.
,rotate
you should make this kind of infobox for EVERY SINGLE FORMULA YOU ENCOUNTER.
what would apply to a ii
you need to identify the shape that QBCR is before you can say what applies to it.
how do I identify it?
you should know all of the various types of triangles and quadrilaterals
so you say "you should know" instead of telling me a proper explanation
sorry m8, if you don't know what say a square or a parallelogram or a trapezoid is then there is nothing i can do for you
then you should be able to identify a square, parallelogram, trapezoid, etc. when you see one
no, because that is something you really should know by this point. if you are unable to plug numbers into a formula then you will not get anywhere at all
"the formula of a trapezoid" makes no sense
the most commonly used formula for THE AREA OF a trapezoid is A = 1/2 (a+b) h, where A is the area, a and b are the bases and h is the height.
yeah still dont know how to find the height
modulus of ai<=1
ai is real
i got kinda far
but the proof is kinda sketch
i assumed for k
then for k+1
i used compound angle
and absolute value of cosine
would appreciate if someone could provide a more formal proof
Let P(N) be the next statement: sin(x1+x2+...+xN) = a1 sin x1 + ... + aN sin xN, where every a_i satisfies |a_i|<=1
P(1) is true: sin(x) = 1*sin x
P(2) is true: sin(x1+x2) = sin x1 * cos x2 + cos x1 * sin x2 = a1 sin x1 + a2 sin x2
Suppose that P is true for some m>=2
Then sin(x1+x2+...+xM) = a1 sin x1 + ... + aM sin xM
P(m+1) is the following:
sin(x1 + x2 + ... + x[m+1]) = a1 sin x1 + a2 sin x2 + ... + aM sin xM + a[m+1] sin x[m+1]
But sin(x1+...+xM+x[m+1]) = sin((x1+...+xM) + x[m+1]) = sin(x1+..+xM) cos x[m+1] + cos (x1+...+) sin x[m+1]
sin and cos will always be somewhere inbetween -1 and 1
If you multiply two numbers absolute value of which is less than or equal to one you will end up with the number which abs is <= 1
Blah blah blah if P(m) is true P(m+1) is true
thanks dord
i was struggling with justifying my conclusion at the end
would it be better to call cos xK+1 a number Ap?
or would that lose generality?
And since
P(1) & for every m P(m)->P(m+1) you get for every n from naturals P(n) is true
I'd suggest calling every cosine something like a_i
"P(1) & for every m P(m)->P(m+1)"
does this just mean true for 1
and if true for m true for m+1?
then true for 2,3........
Well, P(1) is true since sin x = 1 * sin x
And since from P(m) follows P(m+1) using math induction you get that for every natural number P(m) is true
Sure
@heady juniper i can't read your thing well
is it meant to be $\sin\left(\sum_{i=1}^{n} x_i\right) = \sum_{i=1}^n a_i \sin(x_i)$
Ann:
yes
right
@dark sparrow is the 🐐
the what?
goat?
Goat yes
Forgive the terrible paint job 😛 How can I calculate all the points on the yellow curve around the circle given the radius and angle? I'm working on a 2D game and need all the yellow pixels stored in an array.

Amazing!!!

