Math Problem Statement

Find the dimensions of the rectangular corral producing the greatest enclosed area given 200 feet of fencing.

Solution

To find the dimensions of a rectangular corral that produces the greatest enclosed area given 200 feet of fencing, we will use optimization techniques.

Problem Summary:

  • Total perimeter of the rectangular corral: 200 feet.
  • Let the length of the corral be LL and the width be WW.
  • We need to maximize the area AA of the rectangle.

Step 1: Write the perimeter constraint.

The perimeter PP of a rectangle is given by: P=2L+2WP = 2L + 2W Given that P=200P = 200: 2L+2W=2002L + 2W = 200 Dividing through by 2: L+W=100L + W = 100

Step 2: Write the area function.

The area AA of the rectangle is: A=L×WA = L \times W

Step 3: Express AA in terms of one variable.

From the perimeter constraint L+W=100L + W = 100, we can express WW in terms of LL: W=100LW = 100 - L Substitute this into the area function: A=L×(100L)A = L \times (100 - L) A=100LL2A = 100L - L^2

Step 4: Find the critical points.

To find the value of LL that maximizes AA, take the derivative of AA with respect to LL and set it equal to zero: dAdL=1002L=0\frac{dA}{dL} = 100 - 2L = 0 2L=1002L = 100 L=50L = 50

Step 5: Determine WW.

Using W=100LW = 100 - L: W=10050=50W = 100 - 50 = 50

Step 6: Verify that the solution gives a maximum.

Since the area function A=100LL2A = 100L - L^2 is a quadratic function that opens downward (because the coefficient of L2L^2 is negative), the critical point at L=50L = 50 gives a maximum.

Final Answer:

The dimensions of the rectangular corral that produce the greatest enclosed area are:

  • Length: 50 feet
  • Width: 50 feet

The enclosed area is a square with side lengths of 50 feet.

Would you like a detailed explanation of the derivative process or more information about quadratic optimization?

Here are 5 related questions:

  1. How would the solution change if the fencing was 300 feet instead of 200 feet?
  2. What if the corral needs to have a length twice as long as its width?
  3. How would you maximize the area of a rectangular corral with three sides (one side open)?
  4. How does the quadratic nature of the area function ensure a maximum?
  5. What is the difference between finding a maximum and a minimum in calculus?

Tip: For optimization problems, always start by clearly defining your constraint and objective functions.

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Math Problem Analysis

Mathematical Concepts

Optimization
Quadratic Functions
Derivatives

Formulas

Perimeter of a rectangle: P = 2L + 2W
Area of a rectangle: A = L × W
Derivative of the area function: dA/dL = 100 - 2L

Theorems

Quadratic Optimization Theorem: The maximum or minimum of a quadratic function occurs at its vertex.

Suitable Grade Level

Grades 10-12