Question

properties of parallelograms
definition opposite sides are parallel
theorem opposite sides are congruent
theorem opposite angles are congruent
theorem consecutive angles are supplementary
theorem diagonals bisect each other.

Explanation:

Step1: Recall parallelogram properties

Based on geometric definitions and theorems.

Answer:

Definition: Opposite sides are parallel.
Theorem: Opposite sides are congruent.
Theorem: Opposite angles are congruent.
Theorem: Consecutive angles are supplementary.
Theorem: Diagonals bisect each other.