Hyperbolic Sine in terms of Sine

Theorem

 * $\sin \left({ix}\right) = i \sinh x $

where $\sin$ is the sine, $\sinh$ is the hyperbolic sine, and $i^2=-1$.

Also see

 * Cosine of Imaginary Number
 * Tangent of Imaginary Number
 * Cotangent of Imaginary Number
 * Secant of Imaginary Number
 * Cosecant of Imaginary Number