You have the right idea. and describe a sec of points an equal distance away from and respectively, ie a circle.

With questions like this is can really help to draw a diagram.

If you have the equation , this is describing a set of points an equal distance fromand. If you draw a diagram, you will see that the set of points that settle this equation is the perpendicular bisector of the centre of the line, passing through the points and .

Hope this helps

Craig