Question

Integrate sin3xcos3x dx

Answer 1

Let u = sin (3x)
so du = 3 cos(3x) dx

So your integral is of the form u du...the rest is straightforward. Add +C to your aanswer.

Answer 2

caan u explain a bit furter

Answer 3

If u = sin(3x), then the integral takes the form of 1/3 times the integral of u du

Integral of u du is u^2/2...or (sin^2 (3x))/2

final answer is 1/3 times 1.2Sin^2(3x) = 1/6 sin^2(3x) + C