[math-fun] CORRECTED Product formula puzzle

As happens so often, I blew it again. Sorry. Here is the corrected version: the coefficient of the cosine term is 4 (and not 2): ---------------------------------------------------------------- Let N = 2K+1 for some positive integer K. Evaluate explicitly f(N) := Product (5 - 4*cos(2*j*pi/N)) where j runs through 1,2,...,K, and prove your answer. ---------------------------------------------------------------- --Dan _____________________________________________________________________ "It don't mean a thing if it ain't got that certain je ne sais quoi." --Peter Schickele