The opening of China's earliest mathematical work "Parallel Calculation of Classics in Weeks" records a conversation in which Duke Zhou asked Shang Gao for mathematical knowledge.

Duke Zhou asked, "I heard that you are very proficient in mathematics. I want to ask, there is no ladder in the sky to go up, and there is no ruler on the ground to measure. So how can we get the height of heaven and earth? "

Shang Gao replied: "The number comes from the understanding of the other party and the circle." There is a principle: when one right-angled side hook of a right-angled triangle is equal to 3 and the other right-angled side strand is equal to 4, then its hypotenuse chord must be 5. This truth was summed up when Dayu was in charge of water conservancy. "

Definition:

Pythagorean theorem was first proved by Zhao Shuang, a mathematician of the State of Wu in the Three Kingdoms period. The pythagorean square diagram is created, and the pythagorean theorem is proved in detail by combining the shape number. The square ABDE obtained by taking the chord as the side length consists of four equal right triangles and a small square in the middle. The area of each right triangle is ab/2, and the side length of the small square in the middle is b-a, so the area is (b-a)2. That is, the simplified formula is a+b = C.

Impact:

The discovery and proof of Pythagorean theorem by ancient mathematicians in China has a unique contribution and position in the history of mathematics in the world. In particular, the thinking method of "unity of form and number" embodied in it is of great significance to scientific innovation.