The perimeter of the rectangle is 40 cm. Find the length of its unknown sides, one side 6 cm.

From the condition it is known that the perimeter of the rectangle is 40 cm. It is also known that the length of one of the sides is 6 cm. To find the lengths of all sides of the rectangle, we will solve the equation.

A rectangle is a geometric figure in which opposite sides are equal in pairs.

We know the length of one of the sides and the perimeter. To find the second side, we use the formula for finding the perimeter:

P = 2 (a + b);

2 (6 + x) = 40;

6 + x = 40: 2;

6 + x = 20;

x = 20 – 6;

x = 14 cm of the length of the second side of the rectangle.

Answer: 14 cm; 6 cm.