What does "Deg" and "Rad" mean

Deg stands for degrees.  I expect you know what they are.

 

rad stands for radians.  Radians are also used to measure angles. 

 

there are  90 degrees in a right angle              there are    $$\frac{\pi}{2}$$  radians in a right angle

 

there are 180 degrees in a straight angle         there are $$\pi$$  radians in a straight angle

and

360degrees in a revolution.                           there are $$2\pi$$  radians in a revolutions