Pythagoras' Theorem states that h2 = a2 + b2 . This is where you have a right angled triangle, with sides a, b and h where h is the hypotenuse. For example, if we had a triangle with sides of length 3 and 4, and we are trying to find the hypotenuse we would first find h2. This means that h2 = 32 +42so h2 = 9 + 16so h2 = 25therefore the hypotenuse is the square root of 25, so in this case, the hypotenuse would be 5.