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The area of the border is the difference of the area of the larger rectangle and the smaller rectangle.
The dimensions of the smaller rectangle are given: they are 21 meter and 8 meters.
If the uniform width of the border is w (as it is shown in your picture), then the dimensions
of the larger rectangle are 21+2w and 8+2w meters.
So the area of the larger rectangle is (21+2w)*(8+2w) square meters;
the area of the smaller rectangle is 21*8 square meters.
Having this, you can write the equation for the border area
(21+2w)*(8+2w) - 21*8 = 62 square meters.
At this point, the setup is completed.
You have the equation to find w.
This equation is quadratic relative the unknown w.
Reduce/simplify it to the standard form quadratic equation, and then solve it EITHER using the quadratic formula
OR by factoring, if it works.
I hope that from this point you will be able to complete the solution on your own.
If not - then let me know.
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To see many other similar solved problems, see the lessons
- Problems on the area and the dimensions of a rectangle surrounded by a strip
- Problems on a circular pool and a walkway around it
in this site.
Happy learning (!)
Come again to this forum soon to learn something new (!)
