Question 1135656
<br>
The length, width, and diagonal of the rectangle form a right triangle.  This problem is solved in almost no time if you are familiar with the simplest few Pythagorean Triples.<br>
The hypotenuse is 39 = 3*13; one leg (the width) is 15 = 3*5.<br>
5-12-13 is a common Pythagorean Triple; the length is 3*12 = 36.<br>
ANSWER: length = 36 meters