Mihai Cipu, Cyclic quadrilaterals associated with squares,
Forum Geometricorum, 11 (2011) 223--229.
Abstract.
We discuss a family of problems asking to find the geometrical
locus of points P in the plane of a square ABCD having the
property that the i-th triangle center in Kimberling's list with
respect to triangles ABP, BCP, CDP, DAP are concyclic.
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