Question

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.

• A. Statement - 1 is True, Statement - 2 is True, Statement - 2 is a correct explanation for Statement - 1
• B. Statement - 1 is True, Statement - 2 is True : Statement 2 is NOT a correct explanation for Statement - 1
• C. Statement - 1 is True, Statement - 2 is False
• D. Statement - 1 is False, Statement - 2 is True

Answer 1

The correct option is A Statement - 1 is True, Statement - 2 is True, Statement - 2 is a correct explanation for Statement - 1

Curved surface area offrustum $=\pi (r_1+r_2)l,$ where $r_1$
and $r_2$ are radii of frustum and $l$ is a slant height
$=\frac{22}{7}(\frac{9}{\pi }+\frac{3}{\pi })\times 4=\frac{22}{7\times \pi }(9+3)\times 4$
$=\frac{22}{7}\times \frac{7}{22}\left(12\right)\times 4=48c{m}^2$