The Pythagorean theorem or Pythagoras' theorem is a relation in geometry among the three sides of a right triangle.
The theorem is named after the Greek mathematician Pythagoras, who is credited with its discovery and proof, although
it is often argued that knowledge of the theory predates him. (There is much evidence that Babylonian
mathematicians understood the principle, if not the mathematical significance). The theorem is as follows:

The square of the hypotenuse of a right triangle is equal to the sum of the squares on the other two sides



If we let c be the length of the hypotenuse and a and b be the lengths of the other two sides, the theorem can be expressed as the equation:
a^2 + b^2 = c^2,
a^2 + b^2 = c^2,


or to find c:

 c = sqrt{a^2 + b^2}. ,
c = sqrt{a^2 + b^2}. ,


This equation can be rearranged to give the following to find length a or b:

c^2 - a^2 = b^2,
c^2 - a^2 = b^2,
or
c^2 - b^2 = a^2.,
c^2 - b^2 = a^2.,

This theorem can be used to discover length a,b or c in a right angle triangle if the other two are currently known.


external image 180px-Pythagorean.svg.png

This means that the area of the square c is equal to the combination of the areas of boxes a and b.