What approach is used to prove a figure is a trapezoid?

To establish that a figure is a trapezoid, it is essential to demonstrate that there is one pair of opposite sides that are parallel. This definition is fundamental to trapezoids, as they are classified specifically by the presence of at least one pair of parallel sides.

When identifying a trapezoid, focusing on the parallelism of one set of opposite sides effectively confirms its classification. Other attributes, such as the length of sides or the congruency of angles, do not suffice for this classification.

For example, calculating the area or showing that all sides are congruent pertains to different types of quadrilaterals and does not apply specifically to the definition of a trapezoid. Furthermore, proving that all angles are congruent would indicate a rectangle or square but not necessarily a trapezoid, as those shapes have additional properties beyond what is required for a trapezoid.

Thus, demonstrating that only one pair of opposite sides is parallel is the defining characteristic that verifies a figure as a trapezoid.