Brianna is decorating a wreath that has an outer diameter of 18 inches and an inner diameter of 12 inches. What is the maximum area of the wreath that she can cover with decorations?

(1 point)
Responses

141.37 square inches
141.37 square inches

1017.88 square inches
1017.88 square inches

254.49 square inches
254.49 square inches

565.49 square inches

1 answer

To calculate the area of the wreath that Brianna can decorate, we first need to determine the area of the outer circle and subtract the area of the inner circle.

  1. Calculate the radius of the outer circle:

    • The outer diameter is 18 inches, so the radius \( r_{outer} \) is: \[ r_{outer} = \frac{18}{2} = 9 \text{ inches} \]
  2. Calculate the radius of the inner circle:

    • The inner diameter is 12 inches, so the radius \( r_{inner} \) is: \[ r_{inner} = \frac{12}{2} = 6 \text{ inches} \]
  3. Calculate the area of the outer circle: \[ A_{outer} = \pi r_{outer}^2 = \pi (9)^2 = 81\pi \text{ square inches} \]

  4. Calculate the area of the inner circle: \[ A_{inner} = \pi r_{inner}^2 = \pi (6)^2 = 36\pi \text{ square inches} \]

  5. Calculate the area of the wreath: \[ A_{wreath} = A_{outer} - A_{inner} = 81\pi - 36\pi = 45\pi \text{ square inches} \]

  6. Calculate the area in decimal form using \( \pi \approx 3.14 \): \[ A_{wreath} \approx 45 \times 3.14 \approx 141.3 \text{ square inches} \]

Thus, the maximum area of the wreath that Brianna can cover with decorations is approximately \( 141.37 \) square inches.

The correct response is: 141.37 square inches