1. The problem statement, all variables and given/known data Show that arg[(z-1)/(z+1)] represents a circle. Find it's radius and centre. 2. Relevant equations 3. The attempt at a solution using z = (x+iy) i narrowed down to (z-1)/(z+1) = (iy)/(1+x) , assuming it was a circle. What next? Is this correct approach??