9.2 The Pythagorean Theorem – We learned to identify right triangles and use the Pythagorean Theorem. The Pythagorean Theorem states that in any right triangle the sum of the squares of the lengths of the legs is equal to the square of the length of the hypotenuse. We learned that the longest side of each triangle is always the side that is not part of the right angle. The theorem is named for the Greek mathematician Pythagoras who lived about 580 to 500 BC. There is evidence that 1500 years earlier the Babylonians knew the properties of this theorem. An ancient Hindu handbook for Temple builders written around 600 BC states the theorem as well. Pythagoras gets credit because he was the first to demonstrate the truth of the theorem.
We found the length of the hypotenuse in several problems when we were given the two sides adjacent to the right angle in the triangle. Then we found the missing side adjacent to the right angle when we were given the other side and the hypotenuse.