integral 3 sin 3x sin 2x dx

Integral of Trigonometry Function.

∫ 3 sin 3x sin 2x dx
= 3 ∫ [1/2 cos (3x - 2x) - cos (3x + 2x)] dx
= 3/2 ∫ (cos x - cos 5x) dx
= 3/2 (sin x - 1/5 sin 5x) + C
= 3/2 sin x - 3/10 sin 5x + C