Math Problem Statement

The length of a rectangle is five times its width. If the area of the rectangle is 245cm squared, find its perimeter.

Solution

Let's solve this step by step:

  1. Given information:

    • Let the width of the rectangle be ww.
    • The length of the rectangle is 5 times the width, so the length is 5w5w.
    • The area of the rectangle is 245 cm².
  2. Formula for the area of a rectangle: The area AA is given by: A=length×widthA = \text{length} \times \text{width} Substituting the values: 245=5w×w245 = 5w \times w This simplifies to: 245=5w2245 = 5w^2

  3. Solve for ww: Divide both sides by 5: w2=2455=49w^2 = \frac{245}{5} = 49 Now, take the square root of both sides: w=49=7w = \sqrt{49} = 7

    So, the width of the rectangle is 77 cm.

  4. Find the length: Since the length is 5 times the width: Length=5w=5×7=35cm\text{Length} = 5w = 5 \times 7 = 35 \, \text{cm}

  5. Find the perimeter: The formula for the perimeter PP of a rectangle is: P=2×(length+width)P = 2 \times (\text{length} + \text{width}) Substituting the values: P=2×(35+7)=2×42=84cmP = 2 \times (35 + 7) = 2 \times 42 = 84 \, \text{cm}

Thus, the perimeter of the rectangle is 84 cm.


Would you like further details or clarifications?

Here are 5 related questions for practice:

  1. If the width of the rectangle was 10 cm, what would be the length and perimeter?
  2. What would the perimeter be if the area was doubled while keeping the same ratio between length and width?
  3. How would the problem change if the length was 3 times the width instead of 5 times?
  4. Can you find the diagonal of the rectangle using the width and length?
  5. How does the perimeter formula change for a square?

Tip: When solving geometric problems, drawing a diagram can help visualize relationships between different dimensions.

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Math Problem Analysis

Mathematical Concepts

Algebra
Geometry

Formulas

Area of a rectangle: A = length × width
Perimeter of a rectangle: P = 2 × (length + width)
Solving quadratic equations: w^2 = A / length

Theorems

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Suitable Grade Level

Grades 6-8