Evaluate the sum of infinite series.

[meson0731]

Homework Statement

If possible, evaluate the sum :
http://www4a.wolframalpha.com/Calculate/MSP/MSP31841a0i89gaa1b8f5c80000373e40eh779f93h7?MSPStoreType=image/gif&s=17&w=109&h=47

Homework Equations

The Attempt at a Solution

Not really sure what to do. I've tried writing out the terms but its not a geometric series so it didn't help. The only way I can think of is when writing out the first few terms I get something close the the correct answer, which is 0.9659... the numbers get so close together becuase its an alternating series that only the first few terms really matter... but this obviously isn't an accurate way or correct way to do the problem.

 

[Dick]

It looks an awful lot like a Taylor series for the cosine function to me.

 

[meson0731]

ahh your right lol... its just cos(pi/12). Thanks!