Let \(ABCD\) be a convex quadrilateral (convex means that all its internal angles are less than \(180^\circ\), i.e: it doesnt “bulge inwards"). Let \(E\) be the point of intersection of the diagonals. We are told that the triangles \(\triangle AED\) and \(\triangle BEC\) have equal areas. Show that \(AB\) and \(CD\) must be parallel.