By default, Xcas assumes that any angles you use (for example, as the argument to a trigonometric function) are being measured in radians. If you want, you can have Xcas use degrees.
You can set which angle measure Xcas uses in the CAS configuration screen (see Section 3.5.7). Your choice will be stored in the variable angle_radian; this will be 1 if you measure your angles in radians and 0 if you measure your angles in degrees. You can also change which angle measure you use by setting the variable angle_radian to the appropriate value. The angle measure you want to use will be stored in the configuration file (see Section 3.5.10), and so can also be set there.