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Answer:
both figures are parallelograms
Step-by-step explanation:
The diagonals of a quadrilateral bisect each other if and only if that quadrilateral is a parallelogram. Hence, the left figure is a parallelogram.
The opposite angles of a quadrilateral are congruent if and only if that quadrilateral is a parallelogram. Hence the right figure is a parallelogram.
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<em>Additional comment</em>
Proofs of these conditions can be offered, but these are the conclusions of the respective proofs. The bisected diagonals form pairs of triangles, provably congruent using SAS. (left figure) The angles total 360°, so any adjacent pair must total 180°, making opposite sides parallel. (right figure)
