Pythagorean theorem

• Pythagoras' theorem

Named after Pythagoras (from Ancient Greek Πυθαγόρας (Puthagóras)), the Greek mathematician and philosopher who by tradition is credited with the theorem’s discovery and proof.

Pythagorean theorem

1. (geometry) A mathematical theorem which states that the square of the length of the hypotenuse of a right triangle is equal to the sum of the squares of those of the two other sides.

   The Pythagorean theorem only applies to right triangles.

2. (functional analysis) A generalization of the Pythagorean theorem for Euclidean triangles to Hilbert spaces