Portal:Mathematics/Featured picture/2010 09

The Pythagorean theorem, or Pythagoras's theorem, relates the lengths of the three sides of a right triangle, and states:

In any right triangle, the area of the square whose side is the hypotenuse (the side opposite the right angle) is equal to the sum of the areas of the squares whose sides are the two legs (the two sides that meet at a right angle).

There are many proofs of the theorem, dating back to Ancient Greek mathematician Pythagoras, who is credited with its discovery. The above diagram shows a geometric proof.