Explore: Draw a quadrilateral.
Relationship between pairs of opposite sides
As you drag a vertex, do the pairs of opposite sides remain congruent?
Relationship between pairs of opposite angles
As you drag a vertex, do the pairs of opposite angles remain congruent?
Definition of a Parallelogram
Based on your observations in connection to the interior angles of the quadrilateral, which of the following postulates or theorems could you directly use to prove that the opposite sides are parallel?
Proving a quadrilateral is a parallelogram
In the diagram, segment AB is extended past point B. Which postulate(s) or theorem(s) could you use to prove that the quadrilateral is a parallelogram? (Select all that apply.)