Pythagoras (c. 560-c. 480) was a Greek philosopher and religious leader. He made many important contributions to mathematics, astronomy and music theory. Pythagoras is most famous for the theorem on right triangles, a^2 + b^2 = c^2. This theorem was known and discovered in other cultures, even prior to the birth of Pythagoras.

The religious brotherhood that he founded, which amazingly let in women (very radical for that period in time), believed that if people understood numbers that they would understand the divine. They believed that “All is Number.”

Here are some links about the Pythagorean Theorem:

1. Hot Chalk: Multiple representations with diagrams of the proof

2. Nova On-line: an interactive proof with real world examples

3. Go Math: This site has a quick tutorial and problem set with answers.

4. Regents Prep: Has some multiple choice, standardized test practice problems using the Pythagorean theorem

5. Bhaskara’s (c. 1114-1185) Animated Proof of the Pythagorean Theorem