Multiple choice

Find the slant height of a frustum cone whose top radius is 12 cm and bottom radius is 7 cm. The height of the cone is 12 cm.

  1. 15 cm

  2. 13 cm

  3. 10 cm

  4. 14 cm
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B Correct answer
Explanation

Slant height l = sqrt(h^2 + (R-r)^2). l = sqrt(12^2 + (12-7)^2) = sqrt(144 + 25) = sqrt(169) = 13.

AI explanation

The slant height of a frustum is found using the Pythagorean theorem on the difference in radii and the height. The difference between the top and bottom radii is 12 minus 7, which equals 5 cm. The slant height squared equals 5 squared plus 12 squared, giving 25 plus 144, which is 169. Taking the square root of 169 gives a slant height of 13 cm.

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