The perimeter of the parallelogram is 78 cm. Its one side is 15 cm larger than the other. Find the sides of the parallelogram.

In order to find the sides of a parallelogram, we will recall the properties of the sides of a parallelogram and the formula for finding the perimeter of a parallelogram.

It is known from the condition that one of the sides of the parallelogram is 15 cm larger than the second, and its perimeter is 78 cm.

We denote one pair of sides as x cm, then we write the length of the second pair of sides as (x + 15) cm.

P = 2 (a + b);

2 (x + (x + 15)) = 78;

x + x + 15 = 78: 2;

2x + 15 = 39;

2x = 39 – 15;

x = 24: 2;

x = 12 cm is the length of one pair of sides of the parallelogram, then 12 + 15 = 27 cm is the length of the second pair of sides.