RACETRACK DESIGN The accompanying figure depicts a racetrack with ends that are semicircular in shape. The length of the track is 1760 ft (1/3 mi). Find l and r so that the area enclosed by the rectangular region of the racetrack is as large as possible. What is the area enclosed by the track in this case?
![1698_b5f0c11b-0968-4114-963d-2cc2e53af5de.png](https://secure.tutorsglobe.com/CMSImages/1698_b5f0c11b-0968-4114-963d-2cc2e53af5de.png)