Question

Let f (x)

sinx cosx, then f'(x) =
A. Cos2x
B. sin2x
C. tan 2x
D. cos2x - sin2x
​

Answer 1

A. Cos2x

Explanation:

f(x) = sin(x)cos(x) = (1/2) sin(2x) using double angle formula.

f'(x) = ( (1/2)sin(2x) )' = 2(1/2)cos(2x) = cos(2x)