Bojan Hvala, Diophantine Steiner triples and Pythagorean-type triangles,
Forum Geometricorum, 10 (2010) 93--97.

Abstract: We present a connection between Diophantine Steiner triples (integer triples related to configurations of two circles, the larger containing the smaller, in which the Steiner chain closes) and integer-sided triangles with an angle of  60, 90 or 120 degrrees. We introduce an explicit formula and provide a geometrical interpretation.

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