Orthocenter

Not to be confused with Orthocenter (tetrahedron).
The three altitudes of a triangle intersect at the orthocenter, which for an acute triangle is inside the triangle.

The orthocenter of a triangle, usually denoted by H, is the point where the three (possibly extended) altitudes intersect.[1][2] The orthocenter lies inside the triangle if and only if the triangle is acute. For a right triangle, the orthocenter coincides with the vertex at the right angle.[2]

  1. ^ Smart 1998, p. 156
  2. ^ a b Berele & Goldman 2001, p. 118