Let Γ be a circunference and O its center. AE is a diameter of Γ and B the midpoint of one of the arcs AE of Γ. The point D=E in on the segment OE. The point C is such that the quadrilateral ABCD is a parallelogram, with AB parallel to CD and BC parallel to AD. The lines EB and CD meets at point F. The line OF cuts the minor arc EB of Γ at I.Prove that the line EI is the angle bissector of ∠BEC. geometryparallelogramgeometry proposed