Degree (angle) facts for kids
Quick facts for kids Degree 


One degree (shown in red) and 89 degrees (shown in blue)


General information  
Unit system  NonSI accepted unit 
Unit of  Angle 
Symbol  ° or deg 
Conversions  
1 ° in ...  ... is equal to ... 
turns  1360 turn 
radians  π180 rad 
gons  109^{g} 
In mathematics, a degree is a common way to measure plane angle. It is written with the symbol , where corresponds to the entire circle.
It is not an SI unit. The SI uses radian to measure plane angle. However, according to the SI brochure, it is an accepted unit by SI.
History
The actual reason of choosing the degree as a way to measure plane angle is unknown. One theory says that it is related with the fact that a year is approximately 360 days. Some ancient calendars, for example the Persian calendar and the Babylonian calendar, used 360 days for a year.
Another theory says that the Babylonians divided the circle using the angle of an equilateral triangle. The angle was then divided into 60 parts. This is because they used sexagesimal or base60 numeral system.