The degree (°) is the most common unit for measuring angles, dividing a full circle into 360 equal parts. From navigation and construction to everyday geometry, degrees are the default angular unit worldwide. One degree equals π/180 radians or about 0.01745 radians.

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.