Hyperbolic Cotangent of Sum

Theorem

 * $\map \coth {a + b} = \dfrac {\coth a \coth b + 1} {\coth b + \coth a}$

where $\coth$ denotes the hyperbolic cotangent.

Also see

 * Hyperbolic Sine of Sum
 * Hyperbolic Cosine of Sum
 * Hyperbolic Tangent of Sum