What is the largest area that can be fenced off of a rectangular garden if it will be fenced off with 220 feet of available material?

1 Answer
Feb 25, 2015

It will be a square garden.

Let's do the maths:

Let's call the dimensions of the garden xx and yy
Then we can immediately get rid of yy because the circumference of the fence is 220ft220ft, so:

2x+2y=220->2y=220-2x->y=110-x2x+2y=2202y=2202xy=110x

Now we come to area AA (substituting yy)

A=x*y=x(110-x)=110x-x^2A=xy=x(110x)=110xx2

To find the maximum we set the derivative to 00

A'=110-2x=0->x=55->y=110-55=55
(see earlier equation)

Answer : Area A=55*55=3025 ft^2