Limiting point (geometry)

In geometry, the limiting points of two disjoint circles A and B in the Euclidean plane are points p that may be defined by any of the following equivalent properties: The pencil of circles defined by A and B contains a degenerate (radius zero) circle centered at p. Every circle or line that is perpendicular to both A and B passes through p.

Source: Wikipedia — Limiting point (geometry) (CC BY-SA 4.0)