Quadruple Angle Formulas/Hyperbolic Sine

Theorem

 * $\sinh 4 x = 8 \sinh^3 x \cosh x + 4 \sinh x \cosh x$

where $\sinh$ and $\cosh$ denote hyperbolic sine and hyperbolic cosine respectively.

Also see

 * Quadruple Angle Formula for Hyperbolic Cosine
 * Quadruple Angle Formula for Hyperbolic Tangent