The [[Complex Numbers|Complex]] [[Exponential]] is an extension of the definition for exponentiating on the [[Real Numbers|reals]].
$\huge e^{i\theta} = \cos\theta+i\sin\theta $
$\huge \begin{align}
e^{x} &= 1+x+\frac{x^{2}}{2} + \frac{x^{3}}{6} + \cdots \\
&= \sum^{\infty}_{n=0} \frac{x^{n}}{n!}
\end{align}
$