The area of the rectangle is 72 cm2, and one of its sides is 9 cm. Find the second side and perimeter of the rectangle.

Determining the width of the rectangle
The area of ​​a rectangle is the product of the width and the length of the shape.

In literal form, this action can be written as follows:

S = a * b,

Where:

S is the area of ​​the rectangle;
a – the length of the rectangle;
b is the width of the rectangle.
Express the value of the opposite side of the rectangle from the basic formula.

b = S / a.

Substitute the values ​​from the condition and get.

b = 72/9 = 8 cm.

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

P = 2 * (a + b).

Let’s substitute the values ​​from the condition.

P = 2 * (9 + 8) = 2 * 17 = 34 centimeters.

Answer:

The perimeter of the rectangle is 34 cm, the length of the second side is 8 cm.

Solving a similar problem
The task:

The perimeter of a rectangle is 80 cm. Determine its area if one of its sides is 25 cm.

The solution of the problem:

Find the second side of the rectangle.

To do this, we express it from the main formula.

b = (S / 2) – a.

b = (80/2) – 25 = 40 – 25 = 15 cm.

Find the area of ​​the rectangle.

To do this, we multiply the length and width of the rectangle with each other.

15 * 25 = 375 cm ^ 2.

Answer: The area of ​​the rectangle is 375 cm ^ 2.