Thread: Tell me about trigonometric functions

Tell me anything you know about.

Radian and degree measure

Trigonometric functions: (unit Circle)

Right triangle Trigonometry

Trigonometric Functions of any angle

Graphs of sine and Cosine Functions

Graphs of Other trigonometric Functions

I am just interested in it, I've already taken trigonometry, but it takes me a bit to get back into the groove heh.

I actually know alot about all of this, hehe but incase there are things I forgot I wanna know what others think are important from what they remember.

A coterminal function is one which is exactly the same as another when graphed.
e.g. sinA = cos(A - pi/2)
No wait...coterminal is the wrong word. I've gone blank on the right one.

SOCAHTOA


All I ever needed for low level British maths.

It's SOH CAH TOA

Originally Posted by Kushna Mufeed

A coterminal function is one which is exactly the same as another when graphed.
e.g. sinA = cos(A - pi/2)
No wait...coterminal is the wrong word. I've gone blank on the right one.

Coterminal is when the degree or radian rests on the same line in terms of the circular angle which it is given. I.E.

75degree's coterminals are -285, +435, +795, - 645 etc...and then if you want them in radians just multiply them by Pi/180.

Which is what I think you were saying hehe.

That's what I was thinking. What's the name for what I was talking about? I think it's cofunction.

Oh yeah!
pi/180 radians = 1 degree
180 degrees/pi = 1 radian

Not sure...all I know is

Sine = Cosecant
secant = Cosine
Tangent = Cotanget

each one on the opposite side of the = sine is reverse on the division line. r/t = t/r

Hehe had to edit after you edited, aye what you said is right.

Don't forget Euler's formula:

New problem...

sinx(1 - 2(cos^2)x + (Cos^4)x) = (sin^5)x meanwhile i'll be trying to figure it out myself heh.

Oh I figured it out, turns out all you have to do is realize that sin^4x = (sin^2x)(sin^2x) = (-cot^2x +1)(-cot^2x +1) = cos^4x - 2cos^2x + 1 which is means that since cos^4x - 2cos^2x + 1 = sin^4x, when multiplied by sin, sin(cos^4x - 2cos^2x + 1) becomese sin^5x

Please help me with these (any of these) it has been a long time since I went back and did any of these and I seriously need the help. I need it quick too =P.


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