Derivative of Real Area Hyperbolic Cosecant of x over a

Theorem

$\dfrac {\map \d {\arcsch \dfrac x a} } {\d x} = \dfrac {-a} {\size x \sqrt {a^2 + x^2} }$

where $x \ne 0$.

Let $0 < x < a$.

Then $0 < \dfrac x a < 1$ and so:

$\ds \frac {\map \d {\arcsch \dfrac x a} } {\d x}$

$=$

$\ds \frac 1 a \dfrac {-1} {\size {\frac x a} \sqrt {1 + \paren {\frac x a}^2} }$

$\ds $

$=$

$\ds \frac 1 a \frac {-a} {\size x \sqrt {\frac {a^2 + x^2} {a^2} } }$

$\ds $

$=$

$\ds \frac {-a} {\size x \sqrt{a^2 + x^2} }$

$\arcsch \dfrac x a$ is not defined when $x = 0$.

$\blacksquare$