It’s usually called Euler’s Identity, after the great Swiss mathematician Leonard Euler, and several polls of mathematicians and physicists have bestowed on it titles such as “the greatest equation ever”

One of the most important and famous formulas in mathematics is the Pythagorean Theorem: for a right triangle, the square of the long side (hypotenuse) is equal to the sum of the squares of the other two sides. Using a diagram:

As I have pointed out in other posts, proofs of major results like this are [...]