In parallelogram ABCD, E is the mid-point of AD and F is the mid-point of BC. Prove that BFDE is a parallelogram.
Given : || ABCD in which E and F are mid-points of AD and BC respectively.To Prove : BFDE is a || gm.Proof : ∵ E is mid-point of Ad. (Given)∴ DE=12ADAlso F is mid-point of BC (Given)∴ BF=12BCBut AD=BC (opp.~sides of || gm)∴ BF=DEAgain AD || Bc⇒ DE || BFNow DE || BF and DE=BFHence BFDE is a || gm.