Find the sum of cos 1⁰ + cos 2⁰ + cos 23⁰ +…..+ cos 179⁰.

I know the sum would be zero but I can't show how to get it. Please help me to arrive an algebraic.

Printable View

- January 3rd 2011, 06:18 AMvldosum of cosine functions
Find the sum of cos 1⁰ + cos 2⁰ + cos 23⁰ +…..+ cos 179⁰.

I know the sum would be zero but I can't show how to get it. Please help me to arrive an algebraic. - January 3rd 2011, 06:32 AMe^(i*pi)

Take pairs from opposite ends such that

edit: Removed working because as Archie Meade pointed out in post 3 the difference is not 180. The sum is still 180 though and because each sum is 180 the answer is 0 since we're multiplying by 0.

Perhaps it would be better to follow the working in post 3 for a more complete solution - January 3rd 2011, 07:53 AMArchie Meade