English

The altitudes of a triangle

History and Overview 2024-04-01 v1

Abstract

A long-standing, unanswered question regarding Euclid's Elements concerns the absence of a theorem for the concurrence of the altitudes of a triangle, and the possible reasons for this omission. In the centuries following Euclid, a remarkable number of proofs have been put forward; this suggests a search for the most elementary and direct proof. This paper provides a simple, direct, elementary proof of the theorem; it is based solely on the Elements.

Keywords

Cite

@article{arxiv.2403.19670,
  title  = {The altitudes of a triangle},
  author = {Mark Mandelkern},
  journal= {arXiv preprint arXiv:2403.19670},
  year   = {2024}
}
R2 v1 2026-06-28T15:37:30.526Z