The center (or ) of the Nine-Point Circle. It has Triangle Center Function
See also Euler Line, Nine-Point Circle, Nine-Point Conic
References
Carr, G. S. Formulas and Theorems in Pure Mathematics, 2nd ed. New York: Chelsea, p. 624, 1970.
Dixon, R. Mathographics. New York: Dover, pp. 57-58, 1991.
Kimberling, C. ``Central Points and Central Lines in the Plane of a Triangle.'' Math. Mag. 67, 163-187, 1994.
Kimberling, C. ``Nine-Point Center.''
http://cedar.evansville.edu/~ck6/tcenters/class/npcenter.html.