Chapter 20 Chapter Five Pythagorean Forecast

The expression of the Pythagorean theorem in "Nine Chapters" is: "The Pythagorean technique says: Pythagorean shares are multiplied separately, combined, and divided by the square root, that is, the string." That is, c=√(a+b), and a= √(c2), b=√(ca) in two forms.Liu Hui only gave a proof hint: "Hooking self-multiplying is Zhu Fang, stock self-multiplying is Qing Fang, so that entering and exiting complement each other, each according to its type, because the rest does not move. Synthesize the power of the string square, and divide it by opening the square. , that is, the string.” This text is too brief, and later generations have speculated a lot. Figure 14 is a common way of complementing each other.