Diana has 1600 yards of fencing to enclose a rectangular area. Find the dimensions of the rectangle that maximize the enclosed area. What is the maximum area ?

Respuesta :

Answer:

  • 400 yards by 400 yards
  • 160,000 square yards

Step-by-step explanation:

The maximum area polygon for a given perimeter is a regular polygon. The regular 4-sided polygon is the square. Each side length will be ...

  (1600 yd)/4 = 400 yd

The area will be (400 yd)² = 160,000 yd².

The maximum area Diana can enclose is a square 400 yards on each side, for a total of 160,000 square yards.

_____

On dimension can be represented by x, and the other by y. The sum of the two dimensions will be half the perimeter, so we have ...

  y = 800 -x

The area is then ...

  A = xy = x(800 -x)

This equation describes a parabola that opens downward. It has zeros at x=0 and x=800. The vertex (maximum area) is on the line of symmetry halfway between those values, at x = 400. Then y = 800 -400 = 400, and the rectangle is a square.