The golden ratio, 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 about 1: 0.6 18, that is, the long segment is 0.6 18 of the whole segment. 0.6 18 is recognized as the most beautiful scale figure. The above ratio is the ratio that can most arouse people's aesthetic feeling, so it is called the golden section. Application has magical charm in life.

The golden section refers to the point where a line segment is divided into two parts, so that the ratio of the length of the original line segment to the longer part is the golden section. There are two such points on the line segment.

Using two golden points on the line segment, we can make a regular pentagram, a regular pentagon and so on. Let the length of line AB be a, point C be at the golden section near point B, and AC be b,

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