Math Problem Statement

Calculate the area of the shaded region outside two circles (c1 and c2) but inside a rectangle with dimensions 14 cm by 26 cm.

Solution

The image shows two circles, labeled c1c_1 and c2c_2, inside a rectangle. The rectangle has a height of 14 cm and a width of 26 cm. The task is to find the area of the shaded region (yellow) that lies outside the circles but inside the rectangle.

Step-by-step solution:

  1. Calculate the area of the rectangle: Arectangle=width×height=26cm×14cm=364cm2A_{\text{rectangle}} = \text{width} \times \text{height} = 26 \, \text{cm} \times 14 \, \text{cm} = 364 \, \text{cm}^2

  2. Determine the radius of the circles: Since the height of the rectangle is 14 cm and both circles fit perfectly within the height, the diameter of each circle is 14 cm. Therefore, the radius rr of each circle is: r=142=7cmr = \frac{14}{2} = 7 \, \text{cm}

  3. Calculate the area of one circle: The area AcircleA_{\text{circle}} of a circle is given by the formula: Acircle=πr2=π(7cm)2=49πcm2A_{\text{circle}} = \pi r^2 = \pi (7 \, \text{cm})^2 = 49\pi \, \text{cm}^2 So, the area of one circle is approximately: Acircle49×3.1416153.94cm2A_{\text{circle}} \approx 49 \times 3.1416 \approx 153.94 \, \text{cm}^2

  4. Calculate the total area of the two circles: Since there are two identical circles, the total area of the circles is: Atotal circles=2×153.94cm2307.88cm2A_{\text{total circles}} = 2 \times 153.94 \, \text{cm}^2 \approx 307.88 \, \text{cm}^2

  5. Calculate the shaded area: The shaded area is the area of the rectangle minus the total area of the circles: Ashaded=ArectangleAtotal circles=364cm2307.88cm256.12cm2A_{\text{shaded}} = A_{\text{rectangle}} - A_{\text{total circles}} = 364 \, \text{cm}^2 - 307.88 \, \text{cm}^2 \approx 56.12 \, \text{cm}^2

Final Answer:

The shaded area is approximately 56.12 cm².

Would you like more details or have any questions? Here are some related questions:

  1. How would the shaded area change if the circles were smaller?
  2. What would be the formula to calculate the shaded area if there were three circles?
  3. How does the formula for the area of a circle depend on its radius?
  4. What happens to the shaded area if the rectangle's width increases but the circles remain the same?
  5. How would you calculate the shaded area if the circles were not identical?

Tip: Always double-check the units when calculating areas, especially when combining different shapes.

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Math Problem Analysis

Mathematical Concepts

Geometry
Area calculation
Circle properties

Formulas

Area of a rectangle: A = width × height
Area of a circle: A = π × r^2
Radius calculation: r = diameter/2

Theorems

Area difference method

Suitable Grade Level

Grades 6-8