IMO 2021 Shortlist G4
Let ABCD be a quadrilateral inscribed in a circle Ω. Let the tangent to Ω at D intersect the rays BA and BC at points E ...
Category: Geometry
Problem
Let ABCD be a quadrilateral inscribed in a circle Ω. Let the tangent to Ω at D intersect the rays BA and BC at points E and F, respectively. A point T is chosen inside the triangle ABC so that TE k CD and TF k AD. Let K ‰ D be a point on the segment DF such that TD “TK. Prove that the lines AC, DT and BK intersect at one point.