The origin of angle
As we all know, many human cultural heritages were born in the two river basins, and Jiao is one of them. Babylonians were good at astronomy, and their angles were inspired by long-term astronomical observation.
Babylonians found that the sun's orbit in vernal equinox for half a Sunday was exactly equal to 180 sun diameters. Inspired by this, they defined the circumference as 360 degrees and the straight angle as 180 degrees. The corner circle originally represented the sun. In addition, the definition of a straight angle is 180 degrees, which is closely related to the Babylonians' adoption of the hexadecimal method. Finally, because the divisor of 180 is greater than 100 or 200, it has been widely recognized internationally.