Name: Megan Peppenelli

Who is asking: Student
Level: Middle

Question: Why the Pythagorean Theorem so important in our lives and what is it's history?

We have a an answer to an earlier question, called An application of Pythagoras' theorem that contains one example of a use of the Pythagorean Theorem. The theorem however is much more important than this one example shows. Virtually all of trigonometry is based on this theorem. The equation of a circle is just a restatement of the Pythagorean Theorem so anything that uses an algebraic description of a circle used this theorem.

For the history part of your question there is a great web site called The MacTutor History of Mathematics archive that has information on Pythagoras at http://turnbull.dcs.st-and.ac.uk/history/Mathematicians/Pythagoras.html. If you scroll down this page you will find a statement that says that the Babylonians probably knew this fact 1000 years before Pythagoras, but he may have been the first to prove it.