Question

What is the integral of `cos^2(2x)dx`?

Answer 1

`int cos^2(2x)dx = x/2 + 1/8sin(4x) + C`

Explanation:

Use the identity:

`cos^2theta= (1+cos2theta)/2`

so that:

`int cos^2(2x)dx = int (1+cos(4x))/2dx = 1/2intdx + 1/8 int cos(4x)d(4x)= x/2 + 1/8sin(4x) + C`