The source of Pythagorean theorem is Pythagorean tree. This is a basic geometric theorem, which was traditionally proved by Pythagoras in ancient Greece. It is said that Pythagoras cut down a hundred cows to celebrate after proving this theorem, so it is also called the hundred cows theorem. In China, Cai Zhou Shu Jing recorded a special case of Pythagorean theorem. According to legend, it is the discovery of quotient height, so it is also called quotient height theorem; Zhao Shuang in the Three Kingdoms period annotated Pythagorean Theorem in detail in Shu Jing, Cai Zhou to prove this point. France and Belgium are called donkey bridge theorem, and Egypt is called Egyptian triangle. In ancient times, the shorter angle in a right triangle was called hook, the longer angle was called chord, and the hypotenuse was called chord. Pythagorean law is one of the famous theorems in elementary geometry. The sum of the lengths of the squares on the two right angles of a right triangle is equal to the area of the square on the hypotenuse. That is, if the right side length of a right triangle is A and B and the side length is C, then this theorem is widely used after the land submerged by the a*2+b wind river built pyramids and measured the Nile River 4500 years ago. Mathematicians in ancient Babylon (BC 1800 to BC 1600) also proposed many Pythagorean sequences. In the history of mathematics, it is generally believed that Pythagoras first proved this theorem, so many mathematics books call this theorem Pythagoras theorem. There is a famous theorem: in a right triangle, the squares of two right-angled sides are equal to the oblique angle, that is, the square of C is equal to the square of A plus the square of B. Westerners believe that this theorem was discovered by Pythagoras in 500 BC, so it is called Pythagoras theorem. In fact, it is recorded in China's earliest extant mathematical work "The Sutra of Zhou suan", that is, the dialogue between Fang Rong and Chen Zi about this theorem in the 67th century BC. Chen Zi said: The evil (oblique) pythagorean is multiplied separately, and the square disappears. This passage is expressed by a formula: c equals a, and the square of b under the root sign or the square of c equals a square plus b square. Because Chen Zi was earlier than Pythagoras, some people advocated changing its name to Chen Zi Theorem. 1955, named after Pythagorean theorem by China Mathematics in China.