1. The problem statement, all variables and given/known data Determine the boundary of the following set. As usual, z=(x,y). [itex]0<\left| z-z_0 \right|<2[/itex] 2. The attempt at a solution The book's solution says "The circle [itex]\left| z-z_0 \right|=2[/itex] together with the point (0,0)" Why should the answer not be "... together with the point [itex]z_0[/itex]"?