A difference in directions AKA a deviation from one line to another
An actual derived unit that wasn’t just made up, as it describes the arc length of the difference from angle=0
Convert from Degrees to Radians:
An angle that is over 360 degrees, and can be made into an acute angle plus something else
310 degrees = 360 – 50
220 degrees = 180 + 40
So 40 and -50 are the referential angles.
Why 360 Degrees?:
In ancient times 60 was used as it was easy, and then they found out that the unit circle could be divided into 6 equal pieces all being 60 Degrees AKA 6*60 = 360.
Any angle that touches any of the axes, AKA 0, 90, 180, 270, and 360 degrees.
Revolution: Rotation of 360 degrees or 2pi