In plane geometry, the circle is defined as the set of all points at the same distance from an arbitrary point , also belonging to the plane. The great Greek mathematician Apollonius of Perga (c. 262 B.C - 190 B.C.) discovered an alternative way of defining the circle. The circle of Apolonius can be used in the solution of the problem concerning the electrostatic interaction between a conducting sphere and a point charge.
electrostatics; method of images
