|a- b| is the distance from complex numbers a and b so |z- (3+ 4i)| is the distance from 3+ 4i to the point z. The set of all points, z, so that the distance to 3+ 4i is 5 is a circle with center 3+ 4i and radius 5.

|a- b| is the distance from complex numbers a and b so |z- (3+ 4i)| is the distance from 3+ 4i to the point z. The set of all points, z, so that the distance to 3+ 4i is 5 is a circle with center 3+ 4i and radius 5.