# Definition of the Pythagorean Theorem

Although the Pythagorean Theorem was discovered many, many years ago, we continue to be surprised that even today there are more and more diverse fields that require, in one way or another, knowledge of this theorem.

Pythagoras was a philosopher and mathematician in ancient Greece and among his many discoveries in these two important fields of study is the Pythagorean Theorem, also known as hypotenuse theory. We must admit that there is no valid documentation certifying that this transcendental theorem was developed entirely by Pythagoras, but it is true that, after some hard work, he and his group of Pythagoreans were the ones who determined this property that belongs exclusively to right triangles.

To understand the definition of the Pythagorean Theorem we need to understand two fundamental concepts of the theory of right triangles:

1. For a triangle to be considered a right triangle, it must have an interior angle of 90° while the other two are always less than 90°.
2. The sides of a right triangle that form the 90° angle are called “legs”, while the side that is across from this angle is called the “hypotenuse”. The hypotenuse is always longer than the legs in a right triangle, without exception.

If we understand these two basic concepts about right triangles 100%, we won’t have any problem analyzing the relationship given by the Pythagorean Theorem. So, we have that: “In all right triangles, the hypotenuse h raised to the 2nd power is equal to the sum of the same power of each leg l1 and l2.” This expression can be represented symbolically in this way:

h^2 = c1^2 + c2^2