Primitive of Reciprocal of Square of Hyperbolic Cosine of a x plus 1

Theorem

 * $\ds \int \frac {\d x} {\paren {\cosh a x + 1}^2} = \frac 1 {2 a} \tanh \frac {a x} 2 - \frac 1 {6 a} \tanh^3 \frac {a x} 2 + C$

Also see

 * Primitive of $\dfrac 1 {\paren {\cosh a x - 1}^2}$