The radian (rad) is the SI unit of angle measurement, defined as the angle subtended by an arc equal in length to the radius of the circle. It is the natural unit for trigonometric functions in mathematics and physics — sin, cos, and tan all assume radian input. One radian equals approximately 57.296 degrees.

The arcminute (′) equals 1/60 of a degree, used in astronomy, cartography, and precision navigation where fine angular resolution is needed. Stars are cataloged by their coordinates in degrees and arcminutes, and telescope pointing accuracy is often specified in arcminutes. One arcminute equals 1/60 degree or about 0.000291 radians.