6.3 - Proving a Quadrilateral is a Parallelogram

To prove a quadrilateral is a parallelogram.

Time to sharpen up our logical thinking skills...

You have written two-column proofs for algebra equations, for angle and segment measure, for angle pairs when parallel lines were cut by a transversal, and for triangle congruence.

Today we'll use what you have learned previousy about writing proofs, and about triangle congruence and parallel lines cut by a transversal to prove a quadrilateral is a parallelogram.

​Feel free to work with two or three students nearby you.

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Lets's wrap up by working through three proofs on your own. Check in with your classmates with questions. I'll make my way around the room and peek over shoulders.

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​Good work!