The Pythagorean Theory is about right angled
triangles. The Pythagorean theory is sometimes referred to as
the Pythagorean theorem or Pythagoras Theory, after a famous
mathematician, Pythagoras. Below is a video that explains the
Pythagorean Theory and a little of the Pythagorean theorem
proofs.

Pythagorean Theory explained

In case you missed it, the Pythagorean
Theory is given by the formula: