The angle of the five-pointed star is 36°.

The five-pointed star is the polygon with the smallest number of sides. The total degree of the five angles of the five-pointed star is always 180 degrees. Because there are five angles and the degrees of each angle are the same, the reading of each angle is =180°/5=36°.

The earliest use of the pentagram was found in the literature of the Mesopotamian civilization in the ancient Babylonian region, indicating something very similar to pentemychos. Representing the five planets: Jupiter, Mercury, Mars, Saturn and Venus.

The national flag designs of many countries include five-pointed stars: such as Ethiopia, Morocco, Vietnam, North Korea, the Republic of China, the United States, etc. Many times the middle of the pentagon is filled in, removing the division between the pentagon and the five isosceles triangles.

Extended information:

The meaning of the five-pointed star

The five-pointed star has the meaning of "victory". It is used by the armies of many countries as a rank symbol for officers (especially senior officers). It is also often used on flags.

The pentacle is closely associated with the worship of Venus and Venus. Of the various possible reasons for this relationship, the most plausible are the observations of prehistoric astronomers. As seen from Earth, Venus's orbit around the Sun repeats itself every eight years. Its five intersections form an almost perfect five-pointed star.

In ancient Greece and Babylon, the five-pointed star also had special symbolic meaning. The pentagram is the representative symbol of magic and is the symbol of non-Jews. The early Christian church also used five-pointed stars to represent the five wounds of Jesus, but later they mostly represented pagans and Satanists.

In the yin and yang and the five elements of Eastern civilization, the line connecting the five elements to each other happens to be the five-pointed star. In Japan, the five-pointed star is even considered to be the platycodon seal of Abe Seimei.

Reference: Baidu Encyclopedia-Pentagram