# Two Conditions for a Tetrahedron to Be Orthocentric

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An altitude of a tetrahedron is a line from a vertex perpendicular to the face opposite that vertex. A tetrahedron is orthocentric if the four altitudes meet at the same point, which is called the orthocenter or the Monge point.

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Contributed by: Izidor Hafner (April 2017)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

The proof can be found in [1, p. 123].

Reference

[1] V. V. Prasolov and I. F. Sharygin, *Problems in Stereometry* (in Russian), Moscow: Nauka, 1989.

## Permanent Citation

"Two Conditions for a Tetrahedron to Be Orthocentric"

http://demonstrations.wolfram.com/TwoConditionsForATetrahedronToBeOrthocentric/

Wolfram Demonstrations Project

Published: April 25 2017