Primitive of Cosecant of a x/Cosecant minus Cotangent Form

Theorem

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

where $\csc a x - \cot a x \ne 0$.