SOLUTION: State 5 ways to prove that a quadrilateral is a parallelogram?

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Question 394928: State 5 ways to prove that a quadrilateral is a parallelogram?
Answer by Edwin McCravy(20065)   (Show Source): You can put this solution on YOUR website!


1. If both pairs of opposite sides of a quadrilateral are parallel, the
quadrilateral is a parallelogram. (That's the definition of a parallelogram,
the other 5 are theorems that can be proved.)

2. If both pairs of opposite sides of a quadrilateral are congruent, the
quadrilateral is a parallelogram.

3. If one pair of opposite sides of a quadrilateral are both parallel and
congruent, the quadrilateral is a parallelogram.

4. If the diagonals of a quadrilateral bisect each other, the quadrilateral
is a parallelogram.

5. If both pairs of opposite angles of a quadrilateral are congruent, the
quadrilateral is a parallelogram. 

6. If every pair of adjacent angles of a quadrilateral are supplementary, the
quadrilateral is a parallelogram.

Edwin
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