Question

Is `f(x)=cosx*sinx` increasing or decreasing at `x=pi/3`?

Answer 1

decreasing

Explanation:

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

`f'(x) = cos 2x`

`f'(pi/3) = cos ((2pi)/3) = - 1/2`

It is therefore decreasing

graph{cos x sin x [-5, 5, -3, 3]}