The Isogonal Conjugate of the Euler Line. It passes through the vertices of a Triangle, the Orthocenter, Circumcenter, the Lemoine Point, and the Isogonal Conjugate points of the Nine-Point Center and de Longchamps Point.
See also Circumcenter, de Longchamps Point, Euler Line, Isogonal Conjugate, Lemoine Point, Nine-Point Center, Orthocenter
References
Casey, J. A Treatise on the Analytical Geometry of the Point, Line, Circle, and Conic Sections, Containing
an Account of Its Most Recent Extensions with Numerous Examples, 2nd rev. enl. ed. Dublin: Hodges, Figgis, & Co., 1893.
Pinkernell, G. M. ``Cubic Curves in the Triangle Plane.'' J. Geom. 55, 141-161, 1996.
Vandeghen, A. ``Some Remarks on the Isogonal and Cevian Transforms. Alignments of Remarkable Points of a Triangle.''
Amer. Math. Monthly 72, 1091-1094, 1965.