In Fig.8.1, it is given that BDEF and FDCE are parallelograms. Can you say that BD = CD? Why or why not?

∵ BDEF is a parallelogram

∴ BD = FE and BD ∥ FE …(1)

Similarly,

∵ FDCE is a parallelogram

∴ CD = FE and CD ∥ FE …(2)

From (1) and (2),

BD = CD and BD ∥ CD

Hence, BD = CD.