Question

how to integrate sin^2 (3x)

Answer 1

@Jessy96 Do you know the cosine twice of an angle formula?

Answer 2

first convert
sin^2 (3x)=(1/2)(1-cos6x) and then integrate...

Answer 3

integral sin^2(3 x) dx = 1/12 (6 x-sin(6 x))+C