Three concurrent homologous lines pass respectively through three fixed points on the similitude circle which are known as the invariable points.
Invariable Point
See also
Homologous Points, Similitude CircleExplore with Wolfram|Alpha
References
Johnson, R. A. Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle. Boston, MA: Houghton Mifflin, 1929.Referenced on Wolfram|Alpha
Invariable PointCite this as:
Weisstein, Eric W. "Invariable Point." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/InvariablePoint.html