A point about which inversion of two circles produced concentric circles. Every pair of distinct circles has two limiting points. The limiting points correspond to the point circles of a coaxal system, and the limiting points of a coaxal system are inverse points with respect to any circle of the system. To find the limiting point of two circles of radii r and R with centers separated by a distance d, set up a coordinate system centered on the circle of radius R and with the other circle centered at (d, 0).

coaxal system | concentric circles | inverse points | inversion center | point circle