Let S be the set of all complex numbers z satisfying z−2+i≥5 . If the complex number z0 is such that 1z0−1is the maximum of the set 1z−1;z∈S  then the principal argument of 4−z0−z0¯z0−z0¯+2i is

|Z-2+i|≥5⇒(x-2)2+(y+1)2≥5 where Z=x+iy For Z0-1 to be minimum, where Z0=x0+y˙e is at point P on the circle (figure) Arg4-Z0-Z0¯Z0-Z0¯+2i=Arg4-2x02iy0+2i=Arg-i2-x0y0+1=Arg(-iλ) where λ=2-x0y0+1=-π2 (where λ>0 )