If there are many angles, marking the angle will also help the teacher to mark the paper. Teachers are like this. There is no limit to the senior high school entrance examination, but don't mark too much.

There are two ways to express angles, namely, angle system and arc system.

An angle that specifies that one third of the fillet is 1 degree is called angular system. Note that "degree" is a unit, not "1 degree", because the definition of unit is the name of the standard quantity to measure things.