a rancher has 4000 feet of fencing for constructing a rectangular corral. one side of the corral will be formed by a barn and requires no fence. three exterior fences and 2 interior fences partition the corral into 3 rectangular regions. what dimension of the corral maximize the enclosed area? what is the area of that corral?

1 answer

Let x be the width of the corral parallel to the barn and y be the length perpendicular to the barn. The total length of the fencing is given by:

3y + 2x = 4000

We want to maximize the total area A = xy. To do this, we first need to express either x or y in terms of the other variable. From the equation above, we can solve for x:

x = (4000 - 3y)/2

Now, substitute this expression for x into the area equation:

A = y * (4000 - 3y)/2

To maximize the area, we can find the maximum of this function with respect to y by taking the derivative of A with respect to y and setting it equal to 0:

dA/dy = (4000 - 6y)/2

Setting the derivative equal to 0:

0 = (4000 - 6y)/2
0 = 4000 - 6y

Now, solve for y:

6y = 4000
y = 2000/3 ≈ 666.67 feet

Substitute the value of y back into the expression for x:

x = (4000 - 3*666.67)/2 ≈ 1000 ft

Hence, the dimensions of the corral that maximize the enclosed area are approximately 1000 feet by 666.67 feet.

To calculate the maximum area, multiply:

A = 1000 * 666.67 ≈ 667,670 square feet