The pentagram is a figure surrounded by 10 sides, with * * 5 angles, and the sum of the internal angles is 180 degrees, which is radioactive. It is precisely because of this shape of the five-pointed star that it gives people an authoritative, just and fair impression.
The wonder of the five-pointed star lies in mathematics. Everyone knows the famous golden section, and its value is √5- 1÷2, which is about 0.6 18. Divide a line segment into two parts with different lengths, and the ratio of the short part to the long part is equal to the ratio of the long part to the original line segment, which is the golden section. And this famous value is hidden in the pentagram. Look at the picture, there are three points A, B and C on the five-pointed star, BC: AB = AB: AC, which is exactly equal to the golden section.
It is impossible to draw a five-pointed star accurately with bare hands. In some paintings, the inaccurate five-pointed star gives people a relaxed feeling, but in the national flag, national emblem and trademark, the five-pointed star must be completely accurate, and the proportion of any line segment of the five-pointed star must be equal to the golden section. This requires the help of tools. In fact, it is difficult to draw by hand, and it is easy to draw with tools. You can draw with a ruler and compasses without scales, and you can draw with a ruler. The five-pointed star drawn by the following method is absolutely accurate.
1. Draw a point o on a white paper, and draw a circle o with o as the center and an appropriate length as the radius.
2. Make a diameter AZ, and then make a diameter XY perpendicular to it.
3. be the midpoint m of OY.
4. With M as the center and MA as the radius, make an arc ⌒AN and the radius OX intersect at n. ..
5. With A as the center and AN as the radius, cut out equal arcs continuously on the circle, so that the chord AB=BC=CD=DE=AN.
6. Connect AD, AC, EB, EC and BD to get a five-pointed star.