To solve this problem you must apply the proccedure shown below:
1. By definition, the opposite sides of a parallelogram are parallel and have equal length.
2. The figure attached shows that the opposite sides with equal length are:
3. Keeping this on mind, you have that the side <em>c</em> and <em>a</em> are equal and measure six centimeters.
4. To find the length of the other sides, you must apply the following formula for calculate the perimeter of a parallelogram:
4. If you solve for <em>b</em>, you will obtain the measure of <em>b </em>and<em> d:</em>
Therefore the answer is:
The lengths of the sides are: 6 cm, 6 cm, 9 cm and 9 cm.