Decide if the following statements are true or false. If they are true, explain how you know. If they are false, provide a counterexample.
Try to think of a counterexample for each part.
If a quadrilateral has two sides that are parallel and two sides that are congruent, then the quadrilateral must be a parallelogram.
False (isosceles trapezoid)
If the interior angles of a polygon add up to
, then the polygon must be a quadrilateral.
If a quadrilateral has three right angles, then the quadrilateral must be a rectangle.
If the diagonals of a quadrilateral bisect each other, then the quadrilateral must be a rhombus.