Name given to the system for measuring
angles in which the base unit is the
radian.
This system of measurement is called the circular system because of the association between the definition of the
radian and the circle. In
trigonometry, we most often use measures of angles expressed in radians.
Properties
In this system of measurement, the angle corresponding to a complete circle with radius r measures 2π radians and the circumference of this circle is given by C = 2πr.
