The Pythagreon theorem is an important equation in geometry. It is also how you find the hypotanuse of a right triangle. The actual equation is written as a2 + b2 = c2, with a being the measure of 1 side and b being the measure of the other side.  So if you had a right triangle with one side that measured 4 cm and another side that measured 8 cm, then to find the hypotanuse, you would calculate:  4 cm2 + 8 cm2 = c2 16 cm + 64 cm = 80 C (or the hypotanuse of the triangle) = √80, or 8.94 if you know your decimals!