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

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

2. If the interior angles of a polygon add up to $360°$, then the polygon must be a quadrilateral.

   Hint (b):

   Review the Math Notes for information about the interior angles of polygons.

   Answer (b):

   True

3. If a quadrilateral has $3$ right angles, then the quadrilateral must be a rectangle.

   Answer (c):

   True

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