Multiple choice

STATEMENT - 1: The slant height of frustum of a cone is 4 cm. and perimeters of its circular ends are 18 cm. and 6 cm. then the curved surface area is 48 sq. cm. STATEMENT - 2: Curved surface area of frustum $ = \pi (r_1+r_2) $, where $r_1$ and $r_2$ are radii of the frustum and $l$ is a slant height.

  1. Statement - 1 is True, Statement - 2 is True, Statement - 2 is a correct explanation for Statement - 1

  2. Statement - 1 is True, Statement - 2 is True : Statement 2 is NOT a correct explanation for Statement - 1

  3. Statement - 1 is True, Statement - 2 is False

  4. Statement - 1 is False, Statement - 2 is True
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A Correct answer
AI explanation

Dividing the perimeters by 2*pi gives the radii as r1 = 9/pi and r2 = 3/pi, making the sum of the radii 12/pi. The curved surface area formula for a frustum is pi times the sum of the radii times the slant height. Substituting the values gives pi times 12/pi times 4, which equals 48 sq cm, so both the statement and the formula are true.

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