What is the arc length of arc cd in the circle below? circle a is shown with a radius labeled 15 feet and a central angle marked 45 degrees.

The circumference of a circle is found using the formula:

                              , 

where R is the radius of the circle. So the circumference of our circle is 
 
                              (ft).

The ratio of the arc length to the circumference is equal to the measure of the central angle to the complete angle. That is:

                              .

.

11.8 (ft)