Angle measure - degrees and radians

Degrees: a circle may be divided into any number of sectors. The chosen number of devisions is normally 360° (degrees). Angles are further divided into 60 minutes per degree, and sixty seconds per minute.

Radians: are a more natural angle measure, required for many applications.

The radius laid around the circumference subtends an angle of one radian at the center of the circle.

1 One complete turn is 2p radians.

2 Circular arc length is rq where q is in radians.

3 When an angle is small, sinq, tanq, and q in radians, have almost the same value.

Always check that your calculator is set to degrees or to radians, depending on what you are doing.