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locus of P if A'BC, AB'C and ABC' are congruent to ABC

Source: Austrian Federal Competition For Advanced Students 2009, Part 2, p3

August 31, 2019
geometryLocuscongruent triangles

Problem Statement

Let PP be the point in the interior of ABC\vartriangle ABC. Let DD be the intersection of the lines APAP and BCBC and let AA' be the point such that AD=DA\overrightarrow{AD} = \overrightarrow{DA'}. The points BB' and CC' are defined in the similar way. Determine all points PP for which the triangles ABC,ABCA'BC, AB'C, and ABCABC' are congruent to ABC\vartriangle ABC.