The sides of the rectangle are 6 cm and 12 cm. Find the increment of its area if each side is increased by 0.8 cm.

First, we find the initial area of the rectangle.

To do this, we will use the following formula:

S = a * b,

Where:

S is the area of the rectangle;

a – the length of the rectangle (12 cm);

b is the width of the rectangle (6 cm).

We get:

S = 6 * 12 = 72 cm ^ 2.

Find new sides of the rectangle.

6 + 0.8 = 6.8 cm (new width).

12 + 0.8 = 12.8 cm (new length).

We find a new area.

S2 = 12.8 * 6.8 = 87.04 cm ^ 2.

Find the area gain.

To do this, subtract the initial one from the new area.

87.04 – 72 = 15.04 cm ^ 2.

Answer: The area has increased by 15.04 cm ^ 2.