Derivative of Inverse Hyperbolic Cosecant

Theorem
Let $x \in \R_{\ne 0}$.

Let $\csch^{-1} x$ be the inverse hyperbolic cosecant of $x$.

Then:
 * $\map {\dfrac \d {\d x} } {\csch^{-1} x} = \dfrac {-1} {\size x \sqrt {1 + x^2} }$