concurrency wanted, intersecting circumcircles given
Source: 2010 Balkan Shortlist G7 BMO
April 4, 2020
geometrycircumcircleconcurrencyconcurrentprojective geometryradical axis
Problem Statement
A triangle is given. Let be the midpoint of the side of the triangle and the image of point along the line . The circle with center and radius intersects the lines and at the points and respectively. Let be the point of intersection of with the line , and the point of intersection of with the line . The perpendicular from point to the line intersects the lines and at the points and , respectively.
If is the second point of intersection of the circumscribed circles of the triangles and , prove that, the lines and intersect at a common point.