Step-by-step explanation: It shows all sides and diangles, if you were to draw lines with the letters, in different colors, like connect the dots? I don't know for sure and it's not the fanciest. I'm truly sorry, this answer just looks different from the rest. If the quadrilateral has 2 pairs of opposite, congruent sides, it is a parallelogram. If the quadrilateral has consecutive supplementary angles, it is a parallelogram? My second explanation belongs to it's rightful owner and I do not claim it as mine.
