1, principle of complementarity in and out
China's ancient geometry not only has a long history, rich contents and great achievements, but also has its own unique style system, which is different from the western Euclidean system.
The principle of complementary entry and exit (also known as making up for loss with surplus) is that the sum of area or volume remains unchanged after a geometric figure (plane or solid) is divided into several parts. The principle of complementary entry and exit was first founded by Liu Hui, a mathematician of Wei State in the Three Kingdoms period. "Pythagoras each take, and, and prescription, namely string.
Hook multiplied by Zhu Fang, stock multiplied by Fang Qing, the two complement each other. Because the rest do not move, the force of chorus is synthesized and divided into roots, that is, chorus is also. "
In modern languages, the so-called principle of complementarity in and out refers to the obvious fact that a plane figure is displaced from one place to another and its area remains unchanged.
If the graph is divided into several blocks, and the sum of the areas of each part is equal to the area of the original graph, then the sum and difference of the areas before and after the displacement of the graph have a simple equal relationship. The same is true for three dimensions.
By applying this principle, it is easy to get a general formula that the area of a triangle is equal to half of the product of high and low phases, so as to determine the area of any polygon.
2. Liu Hui
Liu Hui (about 225-295), a native of Zouping, Binzhou, Shandong Province, was a great mathematician in Wei and Jin Dynasties and one of the founders of China's classical mathematical theory. He has made great contributions to the history of Chinese mathematics, and his masterpieces "Nine Chapters of Arithmetic Notes" and "Arithmetic on the Island" are the most precious mathematical heritages of China.
Liu Hui has quick thinking and flexible methods. He advocates reasoning and intuition. He was the first person in China who explicitly advocated using logical reasoning to demonstrate mathematical propositions. Liu Hui's life is a life of hard exploration of mathematics.
Although his position is low, his personality is noble. He is not a mediocre man who seeks fame and fame, but a great man who never tires of learning. He left us a valuable fortune.
In May, 20021,the International Astronomical Union (IAU) approved the naming of the lunar landforms in China near the landing site of Chang 'e V, and Liu Hui is one of the eight landforms.