Let △ABC be a triangle and let X be a point in the interior of the triangle. The second intersection points of the lines XA,XB and XC with the circumcircle of △ABC are P,Q and R. Let U be a point on the ray XP (these are the points on the line XP such that P and U lie on the same side of X). The line through U parallel to AB intersects BQ in V . The line through U parallel to AC intersects CR in W. Prove that Q,R,V , and W lie on a circle. geometrycirclescircumcircleConcyclic