Question

The area of a rectangular door is 21 ft. Sq. The border around the door is 20 feet. What is the length and width of the door? Use the factors of 21 to help you find the area of the door first.

Answer 1

Length = 7 feet, and width is 3 feet.

Explanation:

For the given rectangular door,

area = length x width

21 = length x width ................. 1

Also,

perimeter = 2 ( length + width)

20 = 2 ( length + width)

10 = length + width ............ 1

Given that the factors of 21 are required to get the are of the door.

Then, from equation 1;

21 = 7 x 3

And from equation 2;

10 = 7 + 3

So that, the length of the door is 7 feet and its width is 3 feet.