The golden section, also known as Huang Jinlv, means that there is a certain mathematical proportional relationship between the parts of things, that is, the whole is divided into two parts, and the ratio of the larger part to the smaller part is equal to the ratio of the whole to the larger part, and its ratio is 1: 0.6 18 or10/. The above ratio is the ratio that can most arouse people's aesthetic feeling, so it is called the golden section. Divide a line segment into two parts so that the ratio of one part to the total length is equal to the ratio of the other part to this part. One way of golden section is (√5- 1)/2, and the approximate value of the first three digits is 0.6 18. Because the shape designed according to this ratio is very beautiful and soft, it is called golden section, also called Chinese-foreign ratio. This is a very interesting number. We approximate it with 0.6 18, and we can find it by simple calculation:1/0.618 =1.618 (1-0.618). Let's start with a series. The first two numbers are 1 and 1, and each number after it is the sum of the first two numbers. For example: 1, 1, 2, 3, 5, 8, 13, 2 1, 34, 55, 89, 144 ... This series is called Fibonacci series, and these numbers are called Fibonacci series. All triangles that appear after the diagonal of a regular pentagon is full are golden section triangles. The golden triangle has another particularity. All triangles can generate triangles similar to themselves with four congruent triangles, but the golden section triangle is the only triangle that can generate triangles similar to itself with five congruent triangles instead of four congruent triangles. Because the vertex angle of the five-pointed star is 36 degrees, it can also be concluded that the golden section value is 2Sin 18. The golden section is approximately equal to 0.6 18: 1. Regular pentagons and pentagons can be made by dividing two golden sections on a line segment.