September 29–October 5, 2009

Problem

Simplify the expression

E = \cos \left(\frac{\alpha}{2}\right) \cos \left(\frac{\alpha}{4}\right) \cos \left(\frac{\alpha}{8}\right) \cdots \cos \left(\frac{\alpha}{2^n}\right)

Solution

here

List of solvers

James Pfeiffer, Huy Hoang-Nguyen, Nam Namtran, Haowei (undergrad); Chris Green, Travis Willse (grad); Gary Raymond (staff); Marina Meila (faculty); Jake Bryant, Brad Heller, Alejandro Perez, Lloyd Sakazaki, Qiyuan Wei, Congpa You (outside).

James Pfeiffer wins the prize!