Which mathematician’s theorem states that a² + b² = c² for a right triangle?

The theorem stating that a² + b² = c² for a right triangle is the Pythagorean theorem.

In the formula, a and b are the lengths of the two sides meeting at the right angle, while c is the hypotenuse, the side opposite that angle. The relationship lets a solver calculate one side when the other two are known. A triangle whose side lengths satisfy the equation is a right triangle.

The result is named after Pythagoras, a Greek philosopher and mathematician associated with a school in southern Italy during the sixth century BCE. However, versions of the relationship were known earlier. Babylonian mathematical tablets show awareness of Pythagorean triples, and ancient Indian and Chinese texts also contain related geometric results.

The theorem has countless applications in surveying, construction, navigation, physics, and computer graphics. It is distinct from the law of cosines, which generalizes the relationship to triangles that do not contain a right angle.