Euler's Formula

Euler's formula is the following identity in complex analysis making use of the imaginary number $i$:

$e^{i\phi }=\cos \phi +i\sin \phi \!$

Euler's Identity

The formula can be used to derive an equation known as Euler's identity:

$e^{i\pi }+1=0\!$

This is called the most beautiful equation in mathematics, because it equates the five most common mathematical constants in a perfectly elegant manner.

See also

• De Moivre's Theorem
• Leonard Euler
• Arbitrariness or Ambiguity in the Definition of the Imaginary Unit in Mathematics