Euler's Formula
## Formula
$$e^{i\theta}=\cos\theta+i\sin\theta$$
Therefore:
$$z=re^{i\theta}$$
## Conditions / Special Cases
For $\theta=\pi$:
$$e^{i\pi}=-1$$
Hence:
$$e^{i\pi}+1=0$$
## Usage
- Used to convert between polar and exponential forms of a complex number.
- Forms the basis of De Moivre's theorem.