Circular Measure (Radians)

Introduction to Radian Measure

An angle with vertex at the center of a circle that intercepts an arc on the circle equal in length to the radius of the circle has a measure of 1 radian.

                                                      

      

How to Convert Between Degrees and

Radians?

n 1. Multiply a degree measure by π/180  radian and

simplify to convert to radians.

n 2. Multiply a radian measure by 180/π and simplify

to convert to degrees.

Example of Converting from

Degrees to Radians

n Convert each degree measure to radians.

(a) 60°

60° = 60( π/180) = π/3 rad

b) 221.7°

221.7° = 221.7° (π/180) = 3.896 rad

Relationship between degree and Radian