Let ABCD be a trapezoid with AB∥CD and inscribed in a circumference Γ. Let P and Q be two points on segment AB (A, P, Q, B appear in that order and are distinct) such that AP=QB. Let E and F be the second intersection points of lines CP and CQ with Γ, respectively. Lines AB and EF intersect at G. Prove that line DG is tangent to Γ. geometrytrapezoidgeometry solvedIberoamericanprojective geometryMiquel pointgeometry proposed