Amy Bell, Hansen's right triangle theorem, its converse and a generalization,
Forum Geometricorum, 6 (2006) 335--342.

Abstract: We generalize D. W. Hansen's theorem relating the inradius and exradii of a right triangle and its sides to an arbitrary triangle. Specifically, given a triangle, we find two quadruples of segments with equal sums and equal sums of squares. A strong converse of Hansen's theorem is also established.

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