Pythagoras was a Greek philosopher and mathematician. He was the leader of the
Brotherhood of Pythagoreans, a secret society which studied mathematics. Their
motto was "All is number." The Pythagoreans explored the "magic 3-4-5
triangle." This type of triangle was called "magic" because any triangle with
sides of 3, 4, and 5 units always created a right triangle. The Pythagoreans
found that in 3-4-5 triangles, the area of the square of the hypotenuse
equals the sum of the areas of the squares of the other two sides. They then
generalized this rule for 3-4-5 triangles to apply to all right
triangles. Although the theorem is named for Pythagoras, there is evidence that
it may have been known by earlier civilizations.