Given :- ABCD is a QUAD with diagonal BD. 
To prove :- ABCD is a llgm
Proof :- AB = CD =3 cm (given )
             angle CDB = angle ABD = 90 degree (Given )
            If  angle CDB = angle ABD , then AB ll CD ( Angle CDB & angle                 ABD are alternate intr. angles and they are equal )
            Therefore QUAD ABCD is a llgm (A quad with a pair of opposite              sides equal and parallel is a parallelogram. )
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