Units of Angle

Unit	Notes
Radian	Take a circle.  Around the circumference, draw an arc with length equal to the radius of the circle.  Draw two straight lines, one between each end of this arc and the centre.  The angle between the two lines at the centre is one Radian.  There are 2 x PI (approximately 6.2832) radians in one circle.
Degree	There are 360 degrees (o) in a circle.
Minute	There are 60 minutes  (') in a degree.
Second	There are 60 seconds (") in a minute.

Angles smaller than a second are generally expressed as decimal fractions of a second.  So for example, the angle equivalent to 1/13 of a circle would be expressed as:

    27^o 41'  32.31"