Bruno J.

can you do this...

summation n=0 to infinity r^ncosn(theta)=rcos(theta)-r^2/1-2rcos(theta)+r^2

Thank you Bruno.

I'm probably the last person you should ask for tips or advice! I'm not good at this ... Well, I guess at this level that you are you should focus on becoming the best in your class probably if you're not already. I don't know, I think that will give you the confidence that every young math lover needs. Having a good understanding of math is not possible without problem solving, the more the better! Does what I said even make sense? haha ... I hope so.

Thanks for your reply. I am not sure I understand your response. If I understood it correctly I need to have all the number in that case I could very well compare them. The set I am using is a very large set. I am looking for one value out of the set which I could use to test the N whether it falls in that set or not.