Doubling identity for sinh (2)
From specialfunctionswiki
Theorem
The following formula holds: $$\sinh(2z)=\dfrac{2\tanh(z)}{1-\tanh^2(z)},$$ where $\sinh$ denotes hyperbolic sine and $\tanh$ denotes hyperbolic tangent.
Proof
References
- 1964: Milton Abramowitz and Irene A. Stegun: Handbook of mathematical functions ... (previous) ... (next): $4.5.31$
