hey it goes like this
let z be the root
z^n=1
Mod = 1 and arg = 2pik/n
hence the point A0,A1,A2,A3 etc etc are the roots of z^n=1
if you draw a unit circle and place al these roots you will realise that the radius is 1 and its actually equally spaced at an angle of 2pi/n
hence...