Since ABCD is a paraallelogram.
∴ AD||BCNow, AD||BC and transversal BD intersects them at Dand B∴ ∠1=∠2 [Alternate interior angles are equal]
Now, in △ADN and △CBP, we have∠1=∠2∠AND=∠CPB (right angle)
AD = BC [Opposite sides of a || gm are equal]
So, by AAS criterion of congruence
△ADN≅△CBP
AN = CP
[Corresponding parts of congruent triangles are equal]
Hence proved.