Six Properties of Parallelograms 5-2 Proving Quadrilaterals are Parallelograms Six Properties of Parallelograms Opposite sides are parallel. (definition) Opposite sides of a parallelogram are congruent. Opposite angles of a parallelogram are congruent. Diagonals of a parallelogram bisect each other. Consecutive (same-side interior) angles are supplementary. Either diagonal separates the parallelogram into two congruent triangles.
Definition used to prove that Quadrilaterals are Parallelograms If both pairs of opposite sides of a quadrilateral are parallel, then the quadrilateral is a parallelogram.
Theorems used to prove that Quadrilaterals are Parallelograms If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram. If one pair of opposite sides of a quadrilateral are both congruent and parallel, then the quadrilateral is a parallelogram.
(More) Theorems used to prove that Quadrilaterals are Parallelograms If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a parallelogram. If the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram.
Homework Section 5.2 Classroom Exercises (p. 173) #1-9 Section 5.2 Written Exercises (p. 174-175) #1-7, 10, & 19-22