Primitive of Cosecant of a x/Tangent Form

Theorem

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

where $\tan \dfrac {a x} 2 \ne 0$.

Also see

 * Primitive of $\sec a x$: Tangent Form