Math Problem Statement

The rectangle and the square below both have the same perimeter. What is the value of x in cm?

Solution

We are given a rectangle and a square with the same perimeter, and we are asked to find the value of xx in cm.

Step 1: Define the dimensions

  • For the rectangle:
    • Length: x+5x + 5 cm
    • Width: 4 cm
  • For the square:
    • Side length: x+2x + 2 cm

Step 2: Calculate the perimeter of each shape

  • Perimeter of the rectangle: The formula for the perimeter of a rectangle is: Prectangle=2(length+width)P_{\text{rectangle}} = 2(\text{length} + \text{width}) Substituting the values: Prectangle=2((x+5)+4)=2(x+9)P_{\text{rectangle}} = 2((x + 5) + 4) = 2(x + 9)

  • Perimeter of the square: The formula for the perimeter of a square is: Psquare=4×side lengthP_{\text{square}} = 4 \times \text{side length} Substituting the value: Psquare=4(x+2)P_{\text{square}} = 4(x + 2)

Step 3: Set up the equation

Since the perimeters are equal, we can set the two expressions equal to each other: 2(x+9)=4(x+2)2(x + 9) = 4(x + 2)

Step 4: Solve for xx

Expand both sides: 2x+18=4x+82x + 18 = 4x + 8 Now, move all terms involving xx to one side and constant terms to the other: 188=4x2x18 - 8 = 4x - 2x 10=2x10 = 2x Divide by 2: x=5x = 5

Final Answer:

The value of xx is 5\boxed{5} cm.


Would you like further details on the solution, or have any questions?

Here are 5 related questions to explore:

  1. How would the answer change if the perimeter of the rectangle was larger than the square's?
  2. What is the area of the rectangle and the square when x=5x = 5?
  3. How can the formula for perimeter be used for other polygons like triangles or pentagons?
  4. What if the square had a side length of x+3x + 3 cm instead? How would this affect the solution?
  5. How does the perimeter of the rectangle compare to that of the square when the shapes are scaled up proportionally?

Tip: When solving geometry problems, always double-check if the formulas for area and perimeter are applied correctly based on the given shape!

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Math Problem Analysis

Mathematical Concepts

Algebra
Geometry
Linear Equations

Formulas

Perimeter of a rectangle: P = 2(length + width)
Perimeter of a square: P = 4 × side

Theorems

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Suitable Grade Level

Grades 6-8