The perimeter of the rectangle is 18 and the diagonal is 7. Find the area of this rectangle.

In order to find the area of a rectangle, there is a formula:

S = a * b;

The area of a rectangle is equal to the product of the lengths of the sides of the rectangle, but there are also formulas for calculating the area of a rectangle through its perimeter.

Let’s get to know her.

S = (p ^ 2 – 4d ^ 2) / 8.

where p is the perimeter of the rectangle and d is the length of its diagonal.

We just have to substitute the values into the formula and make calculations:

S = (18 ^ 2 – 4 * 7 ^ 2) / 8 = (324 – 196) / 8 = 128/8 = 16 sq. units.

Answer: 16 sq. units.