A quadrilateral has one pair of parallel opposite sides. What additional information could be used to prove that the quadrilateral is a parallelogram?

Answer 1

There are a few other traits to determine whether a quadrilateral is a parallelogram. For one, any given angles beside each other should add up to 180 degrees. These are called supplementary angles. Another trait of a parallelogram is that the sides across from each other should be congruent, or the same length.