# Euler's Formula/Examples/e^i pi

## Example of Use of Euler's Formula

$e^{i \pi} = -1$

## Proof

 $\ds e^{i \pi}$ $=$ $\ds \cos \pi + i \sin \pi$ Euler's Formula $\ds$ $=$ $\ds -1 + i \times 0$ Cosine of $\pi$, Sine of $\pi$ $\ds$ $=$ $\ds -1$

$\blacksquare$

## Also see

This result is significant enough to have its own name: Euler's Identity.