Thunda

e^2 i pi (x/T) => (e^(2 i pi)) ^ (x/T) => 1 ^ (x/T) => 1
integrating both sides from 0 to T w/ respect to x gives
(T/(2 i pi)) e^(2 i pi (x/T))|0, T = T
(T/(2 i pi)) (e^(2 i pi) - 1) = T
T = 0