Trig
posted by jared .
Prove the following functions:
(sinx+sin2x)/(1+cosx+cos2x)=tan x
(cos3x/sinx)+(sin3x/cosx)=2cot2x
tan2x=(2/cotxtanx)
theses are due in the am. Fastness would be great?

You can't prove a function. You can prove an identity.
Using s for sinx, c for cosx, t for tanx, to make things look less cumbersome:
(s+2sc)/(1+c+2c^2  1) = t
(s+2sc)/(c + 2c^2) = t
s(1+2c)/[c(1+2c)] = t
s/c = t
t = t 
tanx