A watchdog is tied to the outside wall of a round building 20 feet in diameter. If the dog's chain is long enough to wind half way around the building, how large an area can the watchdog patrol?
Unless I'm missing something, this is just a circle inside a circle problem.
Area of building (r = 10), pi*r^2 = 100pi. C = piD = 20pi
Chain Area for Dog (r = chain = 10pi), pi*r^2 = pi*(10pi)^2 = 100pi^3.
Patrol area = 100pi^3  100pi, assuming the dog can't get inside the house.

Posted by bob909
on 20041029 12:20:18 