The perimeter of the rectangle is 40 cm and one of its old ones is 4 cm. Find the side of the square

The perimeter of the rectangle is 40 cm and one of its old ones is 4 cm. Find the side of the square equal to the given rectangle.

The first step is to look for the second side of the rectangle. Let’s remember the formula for finding the perimeter.

P = 2 (a + b);

2 (a + 4) = 40;

a + 4 = 40: 2;

a + 4 = 20;

a = 20 – 4;

a = 16 cm.

We are looking for the area of the rectangle according to the formula S = a * b = 4 * 16 = 64 square centimeters.

Since a square is equal in size to a rectangle, their areas are equal.

Let’s remember the formula for finding the area of a square and from it we find the length of the side of the square.

S = a ^ 2;

a ^ 2 = 64;

a = √64;

a = 8 centimeters side of the square.

Answer: 8 centimeters.