Please see the attached file for full problem description.
Q = e^ (i n pi alpha) + e^ (-i n pi alpha)
and Q = 0. How can Q be two different things?© BrainMass Inc. brainmass.com September 23, 2018, 2:25 pm ad1c9bdddf - https://brainmass.com/math/fourier-analysis/fourier-series-proof-24596
The proof is centered on the relations Q = e^ (i n pi alpha) + e^ (-i n pi alpha) and Q =0. The solution is well explained.