a不等于0时,a+ib的幅角就是arctan b/a所以√3/2 - i/2的辐角(a＞0，b＜0)argz=arctan (-1/√3)=arctan (-√3/3)=11π/6所以辐角为2kπ-π/6辐角主值为11π/6
