Primitive of Fourth Power of Sine of a x

Theorem

 * $\ds \int \sin^4 a x \rd x = \frac {3 x} 8 - \frac {\sin 2 a x} {4 a} + \frac {\sin 4 a x} {32 a} + C$

Also see

 * Primitive of $\cos^4 a x$