(e^(iθ)-e(-iθ))/2i=2
(e^(iθ))^2-4i*e(iθ)+1=0
e^(iθ)=(2±√3)i
iθ=log(i(2±√3))
iθ=logi+log(2±√3)
iθ=(π/2+2nπ)i+log(2±√3)
θ=π/2+2nπ-i*log(2±√3) (n∈Z)