Find the side lengths of a rectangle whose area is 51 cm2 and the perimeter is 40 cm.

The perimeter is twice the sum of the sides of the rectangle.

In this case, the sum of the sides of the rectangle will be:

40/2 = 20 cm.

This amount can be decomposed as:

1 + 19 = 20.

2 + 18 = 20.

3 + 17 = 20.

We take the value of the sides equal to 3 and 17 cm.

The area of a rectangle is the product of the sides of the rectangle.

51 cm ^ 2 can be expanded as:

51/3 = 17.

Since 51 is no longer possible to factor into integer factors, we take the sides of the rectangle equal to 3 and 17 cm.

Answer: 3 and 17 cm.