Degrees are a unit that measures angle. A full rotation in degrees is equal to . By convention, degrees are measured starting from the rightmost edge of the circle with the positive direction corresponding to counter-clockwise rotation.

Common Angles Measured in Degrees

Shown below are some common angles measured in degrees. These angles are common since they divide a full rotation into equal parts.

Radian Angle System

Advanced mathematics usually switches to the radian angle system as the preferred unit to measure angles^{[1]}. As a result, calculators often offer an option to toggle between radians and degrees. Some programming languages only use radians for the trigonometric functions and so, if the user wants to use degrees, they need to convert degrees to radians^{[2]}.

Radians are a unit that measure angle using the radius of a circle. One radian is equal to the amount of rotation required to travel the length of one radius along the circumference of the circle.

There are six trigonometric functions that relate to the geometry of the right-triangle sine, cosine, tangent, cosecant, secant, and cotangent. The functions take the angle of a right triangle as input and return a ratio of two of its sides.