Pythagoras’s name is attached to the theorem stating that a² + b² = c² for a right triangle.
The Pythagorean theorem says that the square of the hypotenuse, the side opposite the right angle, equals the sum of the squares of the other two sides. If the legs measure a and b and the hypotenuse measures c, the relationship is a² + b² = c².
The theorem is traditionally associated with Pythagoras, a Greek philosopher and mathematician who lived in the sixth century BC. However, evidence shows that related numerical rules were known before his lifetime. Babylonian mathematical texts, including Plimpton 322, record sets of numbers that fit the relationship.
The theorem works only for right-angled triangles. Its converse is also useful: if a triangle’s side lengths satisfy the equation, the triangle is right-angled. It has applications in surveying, construction, navigation, physics, computer graphics, and distance calculations.