Plane Geometry - Bruce E. Shapiro

Section 38The PythagoreanTheoremThe Pythagorean theorem is perhaps the mostfamous theorem in all of Mathematics; in canbe proven in hundreds of different ways. 1 Itsorigins go back to antiquity, and it is notknown by whom it was first discovered, or evenwho wrote the first proof, although Pythagoras(c. 580 BCE - c.500 BCE) is given credit. 2There is evidence that is already known by theBabylonians and ancient Egyptians by 2500BC. In China it is called the Gougu Theorem,and in India it is known as Bhaskara’s Theorem.A special case was first given (withoutproof) by Baudhayana Baudhayana Sulba Sutra(India, c800 BCE)The rope which is stretched acrossthe diagonal of a square producesan area double the size of the original square.Roman coin with a figureof Pythagoras, madeduring the reign of Decius(249-251) [Wikimedia Commons/PublicDomain Image].1 Elisha Loomis (The Pythagorean Proposition, 1907. Reissued by the NCTM, 1968)contains 367 different proofs of the theorem, one for every day of the year, plus an coupleof extras. A website maintained by Alexander Bogomolny (http://www.cut-the-know.org/pythagoras") contains over 80 proofs.2 For a detailed history see the book by Eli Maor, The Pythagorean Theorem: A 4000Year History, Princeton University Press, 2007.191