Multiple choice

The diameters of two concentric circles are $8$ cm and $10$ cm. The area of the region between them is:

  1. $\pi$ cm$^2$
  2. $3\pi$ cm$^2$
  3. $6\pi$ cm$^2$
  4. $9\pi$ cm$^2$
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D Correct answer
Explanation

Radii are 4 and 5. Area = pi * (5^2 - 4^2) = pi * (25 - 16) = 9pi.

AI explanation

The radii of the two concentric circles are half of their diameters, which are 4 cm and 5 cm. The area of the region between them is found by subtracting the area of the smaller circle from the area of the larger circle, giving pi * (5 squared) - pi * (4 squared). This calculates to 25pi - 16pi = 9pi cm squared.

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