Primitive of Reciprocal of Hyperbolic Cosine of a x minus 1

Theorem

 * $\displaystyle \int \frac {\mathrm d x} {\cosh a x - 1} = -\frac 1 a \coth \frac {a x} 2 + C$

Also see

 * Primitive of $\dfrac 1 {\cosh a x + 1}$