trig derivatives?

Question

what is the derivative of (cos^2 x)?

what is the derivative of (sin^2 x)?

Answer 1

cos^2 x = (cos(x))^2 = f(g(x))
df/dx = df/dg *dg/dx = 2 * cos(x) * sin(x)

Same for sin^2x
-2 * sin(x) * cos(x)