The sides of a parallelogram are 3: 4, its perimeter is 2.8 cm.

In order to find the sides of a rectangle, we will compose and solve equations. To compose it, we will use the formula to find the perimeter of a rectangle.

Let’s look at the condition of the problem. It says that the sides of the parallelogram are 3: 4, and its perimeter is 2.8 cm.

Let’s enter a coefficient of similarity k and write the side lengths as 3k and 4k.

Let’s make the equation:

P = 2 (a + b);

2 (3k + 4k) = 2.8;

3k + 4k = 2.8: 2;

7k = 1.4;

k = 1.4: 7;

k = 0.2.

So, the sides are 3 * 0.2 = 0.6 cm and 4 * 0.2 = 0.8 cm.