Any Help will be Appreciated

DeMoivre's Theorem is this (iis the imaginary unit):

(cos(x) +isin(x)) ^ n = con(nx) +isin(nx)

Let n = 3, and deduce the following

sin(3x) = 3 ((cos(x)) ^ 2) (sin(x)) - (sin(x) ^ 3)

and

cos(3x) = (cos(x) ^ 3) - 3 (cos(x)) (sin(x) ^ 2)

I can simplyify to the point where I need to use the other equation to prove the one I'm on. However, I can't use that unless I have already proved one of them first.