What is the area of the colored region if the radii of the six circles are 1, 2, 3, 4, 5, and 10 centimeters? (Use 3.14 for π. Round to the nearest tenth if necessary.)

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Understand the Problem

The question asks to find the area of the colored region in a figure containing six circles. The radii of the six circles are given as 1, 2, 3, 4, 5, and 10 centimeters. We need to calculate the area of the colored region, using 3.14 for π, and round the answer to the nearest tenth if necessary. This involves calculating the area of the large circle and subtracting the areas of the smaller circles within it.

Answer

B. 141.3 cm²
Answer for screen readers

B. 141.3 cm²

Steps to Solve

  1. Calculate the area of the largest circle The radius of the largest circle is 10 cm. The area of a circle is given by the formula $A = \pi r^2$. We're given that $\pi = 3.14$. So the area of the largest circle is: $A_{large} = 3.14 \times (10)^2 = 3.14 \times 100 = 314 \text{ cm}^2$

  2. Calculate the areas of the smaller circles The radii of the smaller circles are 1, 2, 3, 4, and 5 cm. We need to calculate their individual areas and then sum them up.

$A_1 = 3.14 \times (1)^2 = 3.14 \text{ cm}^2$ $A_2 = 3.14 \times (2)^2 = 3.14 \times 4 = 12.56 \text{ cm}^2$ $A_3 = 3.14 \times (3)^2 = 3.14 \times 9 = 28.26 \text{ cm}^2$ $A_4 = 3.14 \times (4)^2 = 3.14 \times 16 = 50.24 \text{ cm}^2$ $A_5 = 3.14 \times (5)^2 = 3.14 \times 25 = 78.5 \text{ cm}^2$

  1. Calculate the total area of the smaller circles Sum the areas of the smaller circles: $A_{small} = A_1 + A_2 + A_3 + A_4 + A_5 = 3.14 + 12.56 + 28.26 + 50.24 + 78.5 = 172.7 \text{ cm}^2$

  2. Calculate the area of the colored region Subtract the total area of the smaller circles from the area of the largest circle: $A_{colored} = A_{large} - A_{small} = 314 - 172.7 = 141.3 \text{ cm}^2$

B. 141.3 cm²

More Information

The area of the colored region is 141.3 cm². Note that the units should be in cm², since we are calculating area.

Tips

  • Forgetting to use the correct formula for the area of a circle which is $A = \pi r^2$.
  • Incorrectly calculating the square of the radius.
  • Adding the areas of the smaller circles incorrectly.
  • Subtracting in the wrong order, ending up with a negative area.
  • Using the diameter instead of the radius in the area calculation: Always double-check you're using the radius.
  • Using cm³ instead of cm² for area.

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