Pythagoras theorem is called Pythagoras theorem in the west, and it is said that Pythagoras, a mathematician and philosopher of Pythagoras, first discovered it in 550 BC. But the Pythagorean proof method of Pythagorean theorem has been lost. The famous Greek mathematician Euclid gave a good proof in his magnum opus Elements of Geometry (Volume I, Proposition 47).
China discovered and applied this mathematical theorem in ancient times, much earlier than Pythagoras. At the beginning of China's earliest mathematical work, Zhou Pian Shu Jing, there was a conversation in which Duke Zhou asked Shang Gao for mathematical knowledge: "I heard that you are very interested in mathematics.
Very proficient, I would like to ask: there is no ladder to go up in the sky, and the ground can't be measured with a ruler, so how can we get the data about heaven and earth? "Shang Gao replied:" The number comes from the understanding of the other party and the circle. There is a principle: when a right-angled triangle's' moment' gets a right-angled side' hook' equal to 3 and the other right-angled side' strand' equal to 4, then its hypotenuse' chord' must be 5. This truth was summed up when Dayu was in charge of water conservancy.