Euclidean geometry theorem

The Pythagorean Theorem states that in a right-angled triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides (legs).

If $a$ and $b$ are the lengths of the legs and $c$ is the length of the hypotenuse, the theorem is expressed as:

$$a^2 + b^2 = c^2$$