The circumference of the circle in the above figure is 128 ft. what is the length of ab?
a. 16 ft
b. 22.5 ft
c. 105.5 ft
d.45 ft

To answer this question, you should set up a proportion: central angle/360 = arc length/circumference where the central angle = 45 and circumference = 128 ft. After you cross multiply, you should find that the arc length of AB equals 16 ft, which is A.