Y by Rounak_iitr, MathLuis, ehuseyinyigit
Point is the intersection of diagonals of the trapezoid with . Reflections of the lines and into the internal angle bisectors of and intersects the circumcircles of and at and . Line intersects the circumcircle of again at and intersects the circumcricle of again at . Prove that are collinear.
Proposed by Iman Maghsoudi - Iran
Proposed by Iman Maghsoudi - Iran