Abroad, Pythagoras of ancient Greece first proved this theorem. Therefore, it is generally called "Pythagoras Theorem" abroad. It is also said that Pythagoras was ecstatic after completing this theorem and killed 100 cows to celebrate. Therefore, this theorem has also won a mysterious title: "Hundred Cows Theorem".

Pythagoras was a famous mathematician and philosopher in ancient Greece in the fifth century BC. He once founded a school of mysticism: Pythagoras School, which integrates politics, scholarship and religion. Pythagoras' famous proposition "Everything is a number" is the philosophical cornerstone of this school. "All numbers can be expressed as integers or the ratio of integers" is the mathematical belief of this school. Dramatically, however, the Pythagorean theorem established by Pythagoras has become the "grave digger" of Pythagoras' mathematical belief. After the Pythagorean theorem was put forward, hippasus, a member of his school, considered a question: What is the diagonal length of a square with a side length of 1? He found that this length can not be expressed by integer or fraction, but only by a new number. Hippasus's discovery led to the birth of the first irrational number √2 in the history of mathematics. The appearance of small √2 set off a huge storm in the mathematics field at that time. It directly shook the Pythagorean school's mathematical belief and made the Pythagorean school panic. In fact, this great discovery is not only a fatal blow to Pythagoras school. This was a great shock to the thoughts of all the ancient Greeks at that time. The paradox of this conclusion lies in its conflict with common sense: any quantity can be expressed as a rational number within any precision range. This is a widely accepted belief not only in Greece at that time, but also in today's highly developed measurement technology. However, the conclusion that is convinced by our experience and completely in line with common sense is overturned by the existence of a small √2! How contrary to common sense and ridiculous this should be! It just subverts the previous understanding. To make matters worse, people are powerless in the face of this absurdity. This directly led to the crisis of people's understanding at that time, which led to a big storm in the history of western mathematics, known as the "first mathematical crisis."

Two hundred years later, around 370 BC, the brilliant eudoxus established a complete set of proportional theory. His own works have been lost, and his achievements are kept in the fifth chapter of Euclid's Elements of Geometry. Eudoxus's ingenious method can avoid the "logic scandal" of irrational numbers and keep some relevant conclusions, thus solving the mathematical crisis caused by the appearance of irrational numbers. Eudoxus's solution is realized by directly avoiding irrational numbers with the help of geometric methods. This is a rigid dismemberment of numbers and quantities. Under this solution, the use of irrational numbers is allowed and legal only in geometry, but illegal and illogical in algebra. Or irrational numbers are just regarded as simple symbols attached to geometric quantities, not real numbers. Until18th century, mathematicians proved that basic constants such as pi were irrational numbers, and more and more people supported the existence of irrational numbers. /kloc-In the second half of the 9th century, after establishing the real number theory in the present sense, the essence of irrational numbers was thoroughly understood, and irrational numbers really took root in the mathematics garden. The establishment of the legal status of irrational numbers in mathematics, on the one hand, expands human understanding of logarithms from rational numbers to real numbers, on the other hand, truly and completely solves the first mathematical crisis.