Question

Find the area of copper sheet required to make a frustum shaped bucket of height 8 cm and radii 9 cm and 3 cm.

• A. $109c{m}^2$
• B. $129c{m}^2$
• C. $129\pi c{m}^2$
• D. $105c{m}^2$

Answer 1

The correct option is C

$129\pi c{m}^2$

Area of the copper sheet required to make the bucket$=\pi (r_1+r_2)l+\pi r_2^2$, where $l$ is the slant height of the frustum.

$\therefore$ Area of the copper sheet required =
$=\pi (9+3)\times \sqrt{{(9-3)}^2+8^2}+\pi \times 3^2$ $[\because l=\sqrt{{(r_1-r_2)}^2+h^2}]$
$=129\pi c{m}^2$