Degrees and Radians
The value of an angle q can be represented in either degrees or radians. Both are acceptable, and you will need to use both.

Degrees are physically easier to understand. If a vector's direction is -22.6^o, it is apparent which direction this vector points without having to sketch the vector physically. It is not so clear which direction a vector whose angle is -.394 rad points, even though it is the same angle (to 3 SF).

When using your calculator to take the sin, cos, or tan of an angle, be sure that your calculator is set to the same mode (rad or deg) as the "units" of the angle you are inputting.

See angular measurements for more information.