Argand Plane

In the Argands plane what is the locus of z(!=1) such that arg{(3)/(2)((2z^(2)-5z+3)/(2z^(2)-z-2))}=(2 pi)/(3)

Given that |z-a|=a ,and |b-a|=|b-2a|=a where z is a point in the Argand's plane,then the complex number b can be