View source for Pythagorean identity for coth and csch

==Theorem==
The following formula holds:
$$\mathrm{coth}^2(z)-\mathrm{csch}^2(z)=1,$$
where $\mathrm{coth}$ denotes [[coth|hyperbolic cotangent]] and $\mathrm{csch}$ denotes [[csch|hyperbolic cosecant]].

==Proof==

==References==
* {{BookReference|Handbook of mathematical functions|1964|Milton Abramowitz|author2=Irene A. Stegun|prev=Pythagorean identity for tanh and sech|next=Sum of cosh and sinh}}: $4.5.18$