Two roads connect Towns A and B. One passes through Town C which lies between A and B and the other a direct route. The roads are semicircular. Which road will you take if you want to conserve on gas? Why?
Try this problem with your Facebook friends. It’s not that hard. Tricky, maybe. Like the previous problem on area of shaded regions, the challenge is not in finding the answer but in explaining it.
When you are ready, try semicircle problem #2.