MathDB
Standard triangle geometry: BQ bisects CA

Source: problem 9 (G3) of QEDMO 1; created by myself

November 7, 2005
geometrycircumcirclepower of a pointradical axisgeometry proposed

Problem Statement

Let ABCABC be a triangle with ABCBAB\neq CB. Let CC^{\prime} be a point on the ray [AB[AB such that AC=CBAC^{\prime}=CB. Let AA^{\prime} be a point on the ray [CB[CB such that CA=ABCA^{\prime}=AB. Let the circumcircles of triangles ABAABA^{\prime} and CBCCBC^{\prime} intersect at a point QQ (apart from BB). Prove that the line BQBQ bisects the segment CACA. Darij