The current San Francisco cable railway is driven by two large 14-foot-diameter drive wheels, called sheaves. Because of the figure-eight system used, the cable subtends a central angle of 270°on each sheave. Find the length of cable riding on one of the drive sheaves at any given time.

The length of an arc is given by (θ/360)2πr, where θ is the angle subtended by the arc at the center and r is the radius.
The angle θ in this case is 270°, while the radius is 7 feet, diameter is 14 feet
Thus the length of the of the cable will be;
=(270/360)× 22/7×14
= 0.75 × 44
= 33 feet