### Home > GC > Chapter 9 > Lesson 9.1.5 > Problem 9-50

Decide if the following statements are true or false. If they are true, explain how you know. If they are false, provide a counterexample.

If a quadrilateral has two sides that are parallel and two sides that are congruent, then the quadrilateral must be a parallelogram.

If the interior angles of a polygon add up to

, then the polygon must be a quadrilateral. Review the Math Notes for information about the interior angles of polygons.

True

If a quadrilateral has

right angles, then the quadrilateral must be a rectangle. True

If the diagonals of a quadrilateral bisect each other, then the quadrilateral must be a rhombus.

Experiment with the construction in the eTool below.

Click the link at right for the full eTool version:* **9-50a HW eTool*

Experiment with the construction in the eTool below.

Click the link at right for the full eTool version: *9-50d HW eTool*