The Circumcircle of the Fuhrmann Triangle.
See also Fuhrmann Triangle, Mid-Arc Points
References
Fuhrmann, W. Synthetische Beweise Planimetrischer Sätze. Berlin, p. 107, 1890.
Johnson, R. A. Modern Geometry: An Elementary Treatise on the Geometry of the Triangle and the Circle. Boston, MA:
Houghton Mifflin, pp. 228-229, 1929.