1. The problem statement, all variables and given/known data Given f(x) = 2x+1 periodic from -pi<x<pi. Find the fourier series from (-pi to pi) as well as the sine series from [0, pi] and cosine series from (0,pi) 2. Relevant equations 3. The attempt at a solution So since f(x) is periodic it is odd, so then a0 and ak = 0. for bk: bk = 1/pi int f(x) sin kx from -pi to pi. skipping forward, I get bk = [(-1)^ k][-4/k] now im a bit confused about the sine and cosine series. I thought if f(x) was odd then it turns into a sine series automatically so isn't it basically the same thing as what I got? And the cosine series should just be 0?