Find the derivative of f(x)=sin3xf(x) = \sin^3 xf(x)=sin3x.
3sin2xcosx3 \sin^2 x \cos x3sin2xcosx
3sin2x3 \sin^2 x3sin2x
3cos2x3 \cos^2 x3cos2x
cos3x\cos^3 xcos3x