A parallelogram has opposite sides parallel and equal in length. Also opposite angles are equal (angles "A" are the same, and angles "B" are the same). NOTE: Squares, Rectangles and Rhombuses are all Parallelograms!
Also, we have two pairs of parallel sides: is parallel to , and is parallel to . So it is a parallelogram or a rhombus. Since the length of the sides are not equal, the quadrilateral is a parallelogram.