5 circles tangent to three circles
Adrian van Roomen, in 1596, used the geometric statement: Loci of centers of circles tangent to two circels
are two distinct conic sections.
If three circles are defined, then four sets of three conic sections exist, whose common intersections are
centers of circles tangent to the three defined circles.
The common chords of each set of three conic sections are concurrent in the radical center of the three
defined circles.