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Lesson 12-5: Solve Problems Involving Area of Circles — Practice Questions

  1. 1. A slice of a round cake has a radius of $14\text{ cm}$. The outer curved edge of the slice measures $6\text{ cm}$. Using a triangle approximation, estimate the area of the slice in square centimeters. ___

  2. 2. When approximating a circular sector's area as a triangle, which two measurements are used for the triangle's base and height?

    • A. The two radii
    • B. The arc length and the radius
    • C. The arc length and the diameter
    • D. The chord and the arc length
  3. 3. A pendulum with a length of $20\text{ ft}$ swings through an arc of $8\text{ ft}$. Estimate the area of the sector formed by its swing, in square feet. ___

  4. 4. Sector A has a radius of $10\text{ ft}$ and an arc length of $6\text{ ft}$. Sector B has a radius of $5\text{ ft}$ and an arc length of $12\text{ ft}$. How do their estimated areas compare?

    • A. The area of Sector A is larger.
    • B. The area of Sector B is larger.
    • C. Their areas are approximately equal.
    • D. There is not enough information.
  5. 5. A rotating sprinkler waters a sector-shaped area of a lawn. The estimated area watered is $50$ square yards, and the spray reaches a distance of $10$ yards. What is the approximate length of the curved edge of the watered area? ___

  6. 6. A circular garden has a radius of 15 meters. What is its circumference in terms of $\pi$? The answer should be in meters. ___

  7. 7. The circumference of a car tire is $36\pi$ inches. What is the radius of the tire in inches?

    • A. 9
    • B. 18
    • C. 36
    • D. 72
  8. 8. The circumference of a circular tabletop is $52\pi$ cm. What is the diameter of the tabletop in cm? ___

  9. 9. A circular plate has a radius of 10 cm and a measured circumference of 62 cm. Using the formula $C = 2\pi r$, what is the estimated value of $\pi$?

    • A. 3.0
    • B. 3.1
    • C. 3.2
    • D. 6.2
  10. 10. Circle A has a radius of 8 inches. Circle B has a radius that is double the radius of Circle A. How does the circumference of Circle B compare to Circle A?

    • A. It is half as large.
    • B. It is the same.
    • C. It is twice as large.
    • D. It is four times as large.