I will add that figuring out how to evaluate the expression one gets for the answer is not intended to be the crux of the problem. (The evaluation part is part of extremely standard and easy-to-find mathematics literature, including on line.) As for posting the answer, I usually like to wait a few days to do that, if only so that those people who haven't checked their e-mail today will get a chance to think about it. (Will post it Tues. or Weds. if no one else has.) --Dan