Zvonko Cerin, Rings of squares around orthologic triangles,
Forum Geometricorum, 9 (2009) 57--80.

Abstract:  We explore some properties of the geometric configuration when a ring of six squares with the same orientation are erected on the segments BD, DC, CE, EA, AF and FB connecting the vertices of two orthologic triangles ABC and DEF. The special case when DEF is the pedal triangle of a variable point P with respect to the triangle ABC was studied earlier by Bottema, Deaux, Erhmann and Lamoen, and Sashalmi and Hoffmann. We extend their results and discover several new properties of this interesting configuration.

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