WHEW! That is a lot of information about parallelograms! Let's look back at all you have learned.

If a quadrilateral is a parallelogram:

• both pair of opposite sides are parallel
• both pair of opposite sides are congruent
• both pair of opposite angles are congruent
• its consecutive angles are supplementary
• the diagonals bisect each other

Sometimes you have to show that there is enough information to prove that a quadrilateral is a parallelogram. Considering all that you have learned so far, let's look at the conditions necessary to show that a quadrilateral is a parallelogram:

Let's practice recognizing these four conditions.

Look at each diagram below and tell whether or not it is a parallelogram. Be sure to support your answer with one of the conditions above. Click on "Answer" to see if you are correct.

	Is it a parallelogram?
	Interactive popup. Assistance may be required. Answer Yes, the quadrilateral is a parallelogram because both pair of opposite sides are congruent.
	Interactive popup. Assistance may be required. Answer No, the quadrilateral is not a parallelogram because having one pair of angles congruent and one pair of sides congruent is not one of the conditions for proving that a quadrilateral is a parallelogram.
	Interactive popup. Assistance may be required. Answer Yes, the quadrilateral is a parallelogram because one pair of opposite sides are parallel and congruent.
	Interactive popup. Assistance may be required. Answer Yes, the quadrilateral is a parallelogram because both pair of opposite angles are congruent.
	Interactive popup. Assistance may be required. Answer No, there is not enough information to determine whether the quadrilateral is a parallelogram or not.
	Interactive popup. Assistance may be required. Answer Yes, the quadrilateral is a parallelogram because the diagonals bisect each other.