Primitive of Reciprocal of Sine of a x by Square of Cosine of a x

Theorem

 * $\displaystyle \int \frac {\mathrm d x} {\sin a x \cos^2 a x} = \frac 1 a \ln \left\vert{\tan \frac {a x} 2}\right\vert + \frac 1 {a \cos a x} + C$

Also see

 * Primitive of $\dfrac 1 {\sin^2 a x \cos a x}$