Heron triangles and the hunt for unicorns

Fuente: arXiv
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Main Author: Hone, Andrew N. W.
Format: Preprint
Published: 2024
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author Hone, Andrew N. W.
author_facet Hone, Andrew N. W.
contents A Heron triangle is one that has all integer side lengths and integer area, which takes its name from Heron of Alexandria's area formula. From a more relaxed point of view, if rescaling is allowed, then one can define a Heron triangle to be one whose side lengths and area are all rational numbers. A perfect triangle is a Heron triangle with all three medians being rational. According to a longstanding conjecture, no such triangle exists, so perfect triangles are as rare as unicorns. However, if perfect is the enemy of good, then perhaps it is best to insist on only two of the medians being rational. Buchholz and Rathbun found an infinite family of Heron triangles with two rational medians, which they were able to associate with the set of rational points on an elliptic curve $E(\mathbb{Q})$. Here we describe a recently discovered explicit formula for the sides, area and medians of these (almost perfect) triangles, expressed in terms of a pair of integer sequences: these are Somos sequences, which first became popular thanks to David Gale's column in Mathematical Intelligencer.
format Preprint
id arxiv_https___arxiv_org_abs_2401_05581
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Heron triangles and the hunt for unicorns
Hone, Andrew N. W.
Number Theory
Exactly Solvable and Integrable Systems
A Heron triangle is one that has all integer side lengths and integer area, which takes its name from Heron of Alexandria's area formula. From a more relaxed point of view, if rescaling is allowed, then one can define a Heron triangle to be one whose side lengths and area are all rational numbers. A perfect triangle is a Heron triangle with all three medians being rational. According to a longstanding conjecture, no such triangle exists, so perfect triangles are as rare as unicorns. However, if perfect is the enemy of good, then perhaps it is best to insist on only two of the medians being rational. Buchholz and Rathbun found an infinite family of Heron triangles with two rational medians, which they were able to associate with the set of rational points on an elliptic curve $E(\mathbb{Q})$. Here we describe a recently discovered explicit formula for the sides, area and medians of these (almost perfect) triangles, expressed in terms of a pair of integer sequences: these are Somos sequences, which first became popular thanks to David Gale's column in Mathematical Intelligencer.
title Heron triangles and the hunt for unicorns
topic Number Theory
Exactly Solvable and Integrable Systems
url https://arxiv.org/abs/2401.05581