Ways of proving a quadrilaterals are parallelograms

Section 5-2

Using the definition • If both sets of opposite sides are

parallel, then the quadrilateral is a parallelogram.

Using both sets of opposite sides

• If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram

Using one set of opposite sides

• If one pair of opposite sides of a quadrilateral is both congruent, and parallel, then the quadrilateral is a parallelogram

Using opposite angles

• If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a parallelogram

Using Diagonals• If the diagonals of a quadrilateral

bisect each other, then the quadrilateral is a parallelogram.