radian = 180/2pi degrees
The radian measure IS the arc length of the unit circle, by definition - that is how the radian is defined in the first place.
One radian is equal to roughly 57 degrees!
Degree measure is based off of a division of 360 degrees in a circle. Radian measure is based off of a division of 2PI in a full circle.
It is a measure of the extent of angular displacement - a measure of an angle.
Degrees = (180/pi)*Radians