1. By Josh Mitarnowski, Jonathan Sorber, and Kyle Cragle

3.  Both pairs of opposite sides are parallel  Both pairs of opposite sides are congruent  One pair of opposite sides are parallel and congruent  Diagonals bisect each other  Both pairs of opposite angles are congruent  Consecutive angles are supplementary

4.  All the properties of a parallelogram  Has a right angle  Diagonals are congruent

5.  All the properties of a parallelogram  All sides are congruent  Diagonals are congruent  Diagonals bisect the opposite angles

6.  All the properties of a parallelogram  Has a right angle  Diagonals are congruent  All sides are congruent  Diagonals are perpendicular  Diagonals bisect the opposite angles

7.  Exactly one pair of opposite sides are parallel  Exactly two pairs of consecutive angles are supplementary

8.  All the properties of a trapezoid  Non-parallel sides are congruent  Diagonals are congruent  Base angles are congruent

9. ParallelogramBoth pairs of opposite sides are parallel Both pairs of opposite sides are congruent One pair of opposite sides are parallel and congruent Diagonals bisect each other Both pairs of opposite angles are congruent Consecutive angles are supplementar y RectangleAll the properties of a parallelogram Has a right angle Diagonals are congruent RhombusAll the properties of a parallelogram All sides are congruent Diagonals are perpendicular Diagonals bisect the opposite angles SquareAll the properties of a parallelogram Has a right angle Diagonals are congruent All sides are congruent Diagonals are perpendicular Diagonals bisect the opposite angles TrapezoidExactly one pair of opposite sides are parallel Exactly two pairs of consecutive angles are supplementar y Isosceles Trapezoid All the properties of a trapezoid Non-parallel sides are congruent Diagonals are congruent Base angles are congruent

10. If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram. If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a parallelogram. If the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram. If one pair of opposite sides of a quadrilateral is both parallel and congruent, then the quadrilateral is a parallelogram.