In a trapezium ABCD, the sides AB and CD are parallel and the angles ∠ABC and ∠BAD are acute. Show that it is possible to divide the triangle ABC into 4 disjoint triangle X1...,X4 and the triangle ABD into 4 disjoint triangles Y1,...,Y4 such that the triangles Xi and Yi are congruent for all i. geometrytrapezoidgeometry proposed