posted by Sarah Fuller on .
A rear windshield wiper on a car has a total arm length of 10 inches and rotates back and forth through an angle of 95 degrees. The actual wiper blade is 7 inches long. Find the area of thr windshield that is being cleaned.
Take (95/360) of pi*[10^2 -3^2]
Do you see why?
Imagine a 10 inch radius circle with a concentric 3 inch radius circle taken out of the middle. The radial distance from the smaller to the larger radius is 7 inches. Your area is a 95 degree segment of that full circle.