In quadrilateral ABDC, AB // CD. Which additional piece of information is needed to determine that ABDC is a parallelogram? overline AB cong overline CD O overline AC cong overline BD OAB overline AB perp overline BD; overline CD perp overline BD

In quadrilateral ABDC AB CD Which additional piece of information is needed to determine that ABDC is a parallelogram overline AB cong overline CD O overline AC class=