(1-1/2²)(1-1/3²)(1-1/4²)……*(1-1/2008²)
=(1-1/2)(1+1/2)(1-1/3)(1+1/3)·····(1-1/2008)(1+1/2008)
=1/2x3/2x2/3x4/3x3/4x5/3x···x2007/2008x2009/2008
=1/2x2009/2008
=2009/4016