Through the mid-point M of the side CD of a parallelogram ABCD, the line BM is drawn intersecting diagonal AC in L and AD produced in E. Prove that : EL = 2 BL.
1 = 6 (Alternate interior angles)
2 = 3 (Vertically opposite angles)
DM = MC (M is the mid-point of CD)
So, DE = BC (Corresponding parts of congruent triangles)
Also, AD = BC (Opposite sides of a parallelogram)
AE = AD + DE = 2BC
Now, 1 = 6 and 4 = 5