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A rectangular corral of 117 square meters is to be fenced off and then divided by a fence into two​ sections, as shown in the figure to the right. If the cost of fencing for the boundary is ​$10 per meter and the dividing fence costs ​$6 per​ meter, find the dimensions of the corral that minimize the cost of the fencing.

User Premsuraj
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Answer:

the dimensions of the corral that minimize the cost of the fencing are approximately 17.91 meters by 6.54 meters.

Explanation:

Let the length of the corral be x, and the width be y. We know that the area of the corral is 117, so:

xy = 117

We also know that the corral is divided by a fence into two sections. Let the length of one section be L, and the width be y. Then, the length of the other section will be x - L, and the width will still be y. The total fencing cost will be:

10(2x + 2y) + 6(L + 2y)

Simplifying this expression, we get:

20x + 32y + 6L

Using the area equation, we can rewrite this as:

20x + 32(117/x) + 6L

To minimize the cost, we need to take the derivative of this expression with respect to L, and set it equal to zero:

d/dL [20x + 32(117/x) + 6L] = 6 = 0

Solving for L, we get:

L = x/2

Therefore, the two sections of the corral will have equal length. Substituting this value of L into the expression for total fencing cost, we get:

20x + 32y + 3x

Simplifying this, we get:

23x + 32y

Using the area equation to substitute for y, we get:

23x + 32(117/x)

Taking the derivative of this expression with respect to x, and setting it equal to zero, we get:

23 - 3744/x^2 = 0

Solving for x, we get:

x = sqrt(3744/23) ≈ 17.91

Substituting this value of x into the area equation, we get:

y = 117/x ≈ 6.54

Therefore, the dimensions of the corral that minimize the cost of the fencing are approximately 17.91 meters by 6.54 meters.

User Yorgos
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