1. 6 – 3 Proving That a Quadrilateral Is a Parallelogram
L.E.Q. How do you determine whether a quadrilateral is a parallelogram?

2. Theorem 6 – 5: Diagonals of a Quadrilateral Theorem.
If the diagonals of a quadrilateral bisect each other, then it is a parallelogram.

3. Theorem 6 – 6: One Pair of Opposite Sides Theorem.
If one pair of opposite sides of a quadrilateral is both congruent and parallel, then the quadrilateral is a parallelogram.

4. Example 1: Finding Values For Parallelograms.

5. Find values of x and y for which MLPN must be a parallelogram.

6. Find the values of a and c for which PQRS must be a parallelogram.

7. Theorem 6 – 7: Both Pairs of Opposite Sides Theorem.
If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram.

8. Theorem 6 – 8: Both Pairs of Opposite Angles Theorem.
If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a parallelogram.

9. Example 2: Is the Quadrilateral a parallelogram?
Based on the information given, can you determine that the quadrilateral must be a parallelogram? Explain.

14. Homework: Pgs. 307-308 #s 1-15, 26-29 all. Checkpoint Quiz 1
Pg 310 #s 1-10 all.