Which figures are quadrilaterals with at least one pair of parallel sides?

Which figures are quadrilaterals with at least one pair of parallel sides? A trapezoid is a quadrilateral with exactly one pair of parallel sides.

Do all quadrilaterals have at least one pair of parallel lines? Trapezoids have only one pair of parallel sides; parallelograms have two pairs of parallel sides. A trapezoid can never be a parallelogram. The correct answer is that all trapezoids are quadrilaterals. Trapezoids are four-sided polygons, so they are all quadrilaterals.