I'm trying to show that , if y does not equal k (with y and k both being integers). I've tried using the trig identity for the product of sines. That gives , but I'm still stuck there.
Follow Math Help Forum on Facebook and Google+
Your sum is equal to zero if y<>k and:
Last edited by MaxJasper; August 23rd 2012 at 10:28 PM.
View Tag Cloud