One side of the rectangle is 40cm and its perimeter is 210cm. Calculate the area of the rectangle.

We are given a rectangle, one side of which is 40 centimeters, and its perimeter is 210 centimeters, we need to find the area of ​​this rectangle. Let’s start solving:

Because in a rectangle, the length and width are equal to each other, then denoting the letter a – the length, and the letter b – the width, it will be true that the perimeter is: P = (a + b) * 2, then we compose an equation, substitute all the values ​​we know, and the unknown by replacing with the letter x:

210 = 80 * 2x; Now let’s solve this equation:

130 = 2x;

x = 65. Since this side is larger, this is the length.

Now we find the area, it will be equal to: S = a * b = 65 * 40 = 2600 centimeters²

Answer: 2600 cm²