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A triangle with rational sides and rational area is called a rational triangle. In this paper we consider three problems of finding pairs of rational triangles which have a common circumradius as well as either a common perimeter or a…

Number Theory · Mathematics 2021-05-11 Ajai Choudhry

Starting from any given rational-sided, right triangle, for example the $(3,4,5)$-triangle with area $6$, we use Euclidean geometry to show that there are infinitely many other rational-sided, right triangles of the same area. We show…

Number Theory · Mathematics 2019-08-16 Stephanie Chan

In this work, we define a triangle area number to be the area number of a triangle whose sides have integer lengths, and whose area is a rational number. In Result 3, on page 17, we prove that every triangle area number is in fact an…

General Mathematics · Mathematics 2008-04-02 Konstantine D. Zelator

There are four characteristic circles for each triangle on a plane. All for are tangential to the three straight lines containing the triangles' three sides. Three are exterior circles, the fourth is the in-circle. When the triangle is…

General Mathematics · Mathematics 2008-03-26 Konstantine "Hermes" Zelator

A rational triangle is a triangle with rational side lengths. We consider three different families of rational triangles having a fixed side and whose vertices are rational points in the plane. We display a one-to-one correspondence between…

Number Theory · Mathematics 2018-07-23 Mohammad Sadek , Farida shahata

A natural extension of Heron's 2000 year old formula for the area of a triangle to the volume of a tetrahedron is presented. This gives the fourth power of the volume as a polynomial in six simple rational functions of the areas of its four…

Metric Geometry · Mathematics 2025-05-27 Timothy F. Havel

In this paper, we extend the work of \cite{Chahal} in several directions. We first determine all Heron triangles that tightly circumscribe the unit circle and the associated $\tau$-congruent numbers generated by them. We then characterize…

Number Theory · Mathematics 2026-05-28 Shamik Das , Debajyoti De

It is well known that Heron's theorem provides an explicit formula for the area of a triangle, as a symmetric function of the lengths of its sides. It has been extended by Brahmagupta to quadrilaterals inscribed in a circle (cyclic…

History and Overview · Mathematics 2019-10-21 Paolo Dulio , Enrico Laeng

If the four triangular facets of a tetrahedron can be partitioned into pairs having the same area, then the triangles in each pair must be congruent to one another. A Heron-style formula is then derived for the volume of a tetrahedron…

Metric Geometry · Mathematics 2022-11-01 Daniel A. Klain

Heron's formula states that the area $K$ of a triangle with sides $a$, $b$, and $c$ is given by $$ K=\sqrt {s(s-a) (s-b) (s-c)} $$ where $s$ is the semiperimeter $(a+b+c)/2$. Brahmagupta, Robbins, Roskies, and Maley generalized this formula…

Metric Geometry · Mathematics 2012-03-16 Marshall W. Buck , Robert L. Siddon

In this paper we consider the problem of finding pairs of triangles whose sides are perfect squares of integers, and which have a common perimeter and common area. We find two such pairs of triangles, and prove that there exist infinitely…

Number Theory · Mathematics 2021-04-14 Ajai Choudhry , Arman Shamsi Zargar

By Fermat's method, we show that there are infinitely many Heron triangle and $\theta$-integral rhombus pairs with a common area and a common perimeter. Moreover, we prove that there does not exist any integral isosceles triangle and…

Number Theory · Mathematics 2017-07-04 Yong Zhang , Junyao Peng

A convex polygon is Heronian if its side lengths and its area are integers. Two polygons are amicable if the area of one is equal to the perimeter of the other, and vice versa. We show that there are infinitely many pairs of amicable…

Metric Geometry · Mathematics 2025-05-20 Iwan Praton , Weiran Zeng

In "Unsolved Problems in Number Theory" problem D22 Richard Guy asked for the existence of simplices with integer lengths, areas, volumes... In dimension two this is well known, these triangles are called Heron triangles. Here I will…

Number Theory · Mathematics 2007-05-23 Jan Fricke

The aim of this paper is to introduce a new family of elliptic curves with positive ranks. These elliptic curves have been constructed with certain rational numbers, namely a, b, and c as sides of Heron triangles having rational areas $k$.…

Number Theory · Mathematics 2015-01-20 F. A. Izadi , Foad Khoshnam , K. Nabardi

It is easy to find a right-angled triangle with integer sides whose area is 6. There is no such triangle with area 5, but there is one with rational sides (a `\emph{Pythagorean triangle}'). For historical reasons, integers such as 6 or 5…

Number Theory · Mathematics 2007-12-27 Alf van der Poorten

We indicate that Heron's formula (which relates the square of the area of a triangle to a quartic function of its edge lengths) can be interpreted as a scissors congruence in 4-dimensional space. In the process of demonstrating this, we…

History and Overview · Mathematics 2015-04-09 J. Scott Carter , David A. Mullens

In this work, we prove that any triangle whose three sidelengths are integers, cannot have all of its three medians also having integral lengths.This is done in Proposition 2.In Section 5, we give precise(i.e.necessary and…

General Mathematics · Mathematics 2013-08-16 Konstantine Zelator

Magic squares are well-known arrangements of integers with common row, column, and diagonal sums. Various other magic shapes have been proposed, but triangles have been somewhat overlooked. We introduce certain triangular arrangements of…

General Mathematics · Mathematics 2022-08-29 Gabriel Hale , Bjorn Vogen , Matthew Wright

If we label the vertices of a triangle with 1, 2 and 4, and the orthocentre with 7, then any of the four numbers 1, 2, 4, 7 is the nim-sum of the other three and is their orthocentre. Regard the triangle as an orthocentric quadrangle.…

History and Overview · Mathematics 2019-10-09 Richard K. Guy