Question

Find the maximum area for a rectangle with a perimeter of 120 meters.

Answer 1

900 m^2

Explanation:

Let x = length, y = width

perimeter = 2x + 2y = 2(x + y) = 120. so

x + y = 60, or y = 60 - x

Area = xy = x(60 - x) = 60x - x^2

= -(x^2 - 60x + 30^2) + 30^2

= 900 - (x - 30)^2

Note (x - 30)^2 is never negative, at least zero.

When (x - 30) = 0, the area is the largest which is 900 m^2