I agree 100% !
It would be a circle in with radius
which is what u have.
Describe the given set with a single equation or with a pair of equations:
The set of points in space that lie 2 units from the point (0,0,1) and, at the same time, 2 units from the point (0,0,-1).
I got the circle x^2 +y^2=3, z=0
is this correct?