Question

Evaluate the integral: ∫sin 8x/√(9 + sin44x) dx

Answer 1

Suppose t = sin2 4x

dt = (2sin 4x cos 4x) x (4 dx)

As we know sin 2x = 2sin 2x cos 2x

So, dt = 4sin 8x dx

or sin 8x dx = dt/4