Remember that the radian measure of a central angle of a circle is the ratio of the arc length to the radius (see problem 10-55). is blue.  

1. What is the radian measure for a $45$-degree central angle on a circle with radius $5$ cm? What is the radian measure for a $45$-degree central angle on a circle with radius $1$ cm? Answer in terms of $π$.

   Hint (a):

   Both answers in part a should be the same.

2. The central angle of a circle has a radian measure of $\frac { \pi } { 3 }$. What is the measure of the central angle of the sector in degrees?

• Answer (b):

  $60º$