Question

How do you find the derivative of `(cosx)(sinx)`?

Answer 1

Use `sin(2a) = 2sinAcosA` to rewrite.

Explanation:

`y = cosx sinx = 1/2 sin(2x)`

`y' = 1/2 [cos(2x) * d/dx(2x)] = 1/2 cos(2x)*2 = cos(2x)`