Orthic Triangle
Given a Triangle 
,the Triangle 
with Vertices at the feet of the Altitudes (perpendiculars from a point to the sides) is called the orthic triangle. The threelines 
are Concurrent at the Orthocenter 
of .
The centroid of the orthic triangle has Triangle Center Function
(Casey 1893, Kimberling 1994). The Orthocenter of the orthic triangle has Triangle Center Function
(Casey 1893, Kimberling 1994). The Symmedian Point of the orthic triangle has Triangle Center Function
(Casey 1893, Kimberling 1994).See also Altitude, Fagnano's Problem, Orthocenter, Pedal Triangle, Schwarz's Triangle Problem, Symmedian Point
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 ed., rev. enl. Dublin: Hodges, Figgis, & Co., p. 9, 1893. Coxeter, H. S. M. and Greitzer, S. L. Geometry Revisited. Washington, DC: Math. Assoc. Amer., pp. 9 and 16-18, 1967. Kimberling, C. ``Central Points and Central Lines in the Plane of a Triangle.'' Math. Mag. 67, 163-187, 1994.
- Heptakaidecagon
- Heptaparallelohedron
- Heptomino
- Herbrand's Theorem
- Hereditary Representation
- Heredity
- Hermann Grid Illusion
- Hermann-Hering Illusion
- Hermann-Mauguin Symbol
- Hermann's Formula
- Hermite Constants
- Hermite Differential Equation
- Hermite-Gauss Quadrature
- Hermite Interpolation
- Hermite-Lindemann Theorem
- Hermite Polynomial
- Hermite Quadrature
- Hermite's Interpolating Polynomial
- Hermite's Theorem
- Hermitian Form
- Hermitian Matrix
- Hermitian Operator
- Hermit Point
- Heronian Tetrahedron
- Heronian Triangle