De Moivre's Formula

Theorem

 * $\left({\cos x + i \sin x}\right)^n = \cos \left({n x}\right)+ i \sin \left({n x}\right)$, for $\begin{cases} n = 1, 2, 3, \ldots \\ x \in \R \end{cases}$

Also known as
De Moivre's Theorem.