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. In fact, this mathematical theorem was discovered and applied in ancient China much earlier than Pythagoras. If it can't be verified that Dayu's flood control is a long time ago, then the dialogue between Duke Zhou and Shang can be determined in the Western Zhou Dynasty around 1 100 BC, more than 500 years earlier than Pythagoras. Hooking 3 strands, 4 strings and 5 strings is a special application of Pythagorean theorem (32+42=52). So now the mathematical world calls it Pythagorean Theorem.