Find the side of the rectangle if its perimeter is 40 cm and the length is 12 cm.

Find the side of the rectangle if its perimeter is 40 cm and the length is 12 cm. Find out the area of this rectangle.

1) Find the sum of the two sides, the length and width of the rectangle. The perimeter of a rectangle is equal to the sum of the lengths of its sides. P = 2 (a + b). The sum of the length and width of the rectangle is half the perimeter.

40: 2 = 20 (cm).

2) Find the width of the rectangle.

20 – 12 = 8 (cm).

3) Find the area of the rectangle. The area of a rectangle is equal to the product of its sides. S = ab.

12 * 8 = 96 (cm ^ 2).

Answer. 8 cm; 96 cm ^ 2.