Allan J. Macleod, On integer relations between the area and perimeter of Heron triangles,
Forum Geometricorum, 9 (2009) 41--46.

Abstract:   We discuss the relationship P^2 = nA for a triangle with integer sides, with perimeter P and area A, where n is an integer. We show that the problem reduces to finding rational points of infinite order in a family of elliptic curves. The geometry of the curves plays a crucial role in finding real triangles.

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