Math Problem Statement

What is the maximum possible area of a rectangle is square unit of length 16 units? A. 128 B. 64 C. 48 D. 256

Solution

The maximum possible area of a rectangle given a perimeter of 16 units can be found by recognizing that, for a fixed perimeter, a square gives the maximum area.

Step-by-step solution:

  1. The formula for the perimeter of a rectangle is: P=2×(L+W)P = 2 \times (L + W) where LL is the length and WW is the width. Given P=16P = 16, we have: 2×(L+W)=162 \times (L + W) = 16 Simplifying this: L+W=8L + W = 8

  2. The area of the rectangle is: A=L×WA = L \times W To maximize the area, we express WW in terms of LL using L+W=8L + W = 8: W=8LW = 8 - L So, the area becomes: A=L×(8L)A = L \times (8 - L) Expanding this: A=8LL2A = 8L - L^2

  3. To find the maximum area, take the derivative of the area function with respect to LL and set it to zero: dAdL=82L=0\frac{dA}{dL} = 8 - 2L = 0 Solving for LL: 2L=8    L=42L = 8 \implies L = 4

  4. Since L+W=8L + W = 8, if L=4L = 4, then W=4W = 4. Therefore, the rectangle is a square with side lengths of 4 units.

  5. The area of this square is: A=4×4=16 square unitsA = 4 \times 4 = 16 \text{ square units}

Thus, the maximum possible area of a rectangle with a perimeter of 16 units is 16 square units. None of the answer choices listed are correct.

Would you like further details or have any questions?

Related questions:

  1. What is the relationship between perimeter and area for different rectangles?
  2. How does maximizing the area of a rectangle relate to optimization in calculus?
  3. How do you calculate the perimeter of a square?
  4. How does the area of a rectangle change if one side is doubled?
  5. How would the maximum area change if the perimeter were increased?

Tip: For a fixed perimeter, the rectangle with the largest area is always a square.

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Math Problem Analysis

Mathematical Concepts

Geometry
Optimization
Perimeter and Area Relationship

Formulas

Perimeter of a rectangle: P = 2(L + W)
Area of a rectangle: A = L * W
Maximization function: A = L * (8 - L)

Theorems

For a fixed perimeter, the maximum area of a rectangle occurs when it is a square

Suitable Grade Level

Grades 7-10