# What is meant by the term "two radians"?

Radian measure of an angle is defined by constructing a circle of radius $r$ with center at the vertex of the angle. The length of the arc on the circle defined by the angle is denoted $s$. The radian measure of the angle is the ratio $\frac{s}{r}$.
An angle of 2 radians cuts off an arc of length $2 r$ when placed at the center of a circle of radius $r$.
(Placed at the center of a circle of radius $3$cm, an angle of measure 2 radians cuts off an arc of length #6 cm)