Is the quadrilateral shown here a parallelogram?  

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justaguide eNotes educator| Certified Educator

In the figure provided, let A, B, C and D represent the vertices starting from the top left and moving in a clockwise direction.

It is given that AB = CD. Also, the adjacent angles A and D are supplementary.

If a four sided polygon has a set of opposite sides that are equal in length and if the adjacent angles are supplementary, the polygon is a parallelogram.

The figure in the link provided is a parallelogram.