Question

think - pair - share
if the argument is \all rectangles have opposite sides parallel; therefore, given a quadrilateral is not a rectangle, the quadrilateral does not have opposite sides parallel.\
provide a counterexample to show that the concluding statement of the argument is not valid.

Explanation:

Step1: Analyze the argument

The argument wrongly assumes that only rectangles have opposite - sides parallel.

Step2: Consider a counter - example

A trapezoid is a quadrilateral that is not a rectangle. A trapezoid has one pair of opposite sides parallel.

Answer:

A trapezoid is a valid counter - example as it is a non - rectangle quadrilateral with at least one pair of parallel sides.