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TOT 250 1990 Spring A J4 collinear wanted, rhombus

Source:

March 12, 2021
geometryrhombuscollinear

Problem Statement

Let ABCDABCD be a rhombus and PP be a point on its side BCBC. The circle passing through A,BA, B, and PP intersects BDBD once more at the point QQ and the circle passing through C,PC,P and QQ intersects BDBD once more at the point RR. Prove that A,RA, R and PP lie on the one straight line.
(D. Fomin, Leningrad)