Question

given : parallelogram abcd in which diagonal ac and bd intersect m. prove : m is mid=point of ln

Answer 1

In  ΔAML and ΔCMN

              ∠MAL = ∠MCN(alternate interior angles)

              ∠AML = ∠CMN(vertically opposite angles)

              AM = CM (diagonals in a parallelogram bisect each other)

          ∴ ΔAML ≈ ΔCMN

       ∴LM = NM (cpct)

   ∴M is the  midpoint of ln