Surface Areas and Volumes — Maths STD 9 — Question

3. 220m

Solution:

Let the length of the required cloth be L m and its breadth be B m.

Here, B = 2.5m

Radius of the conical tent = 7m

Height of the tent = 24m

Area of cloth required = curved surface area of the conical tent

$\Rightarrow\text{L}\times\text{B}=\pi\text{rl}​​$

$\Rightarrow\text{L}\times\text{B}=\pi\text{rl}​​$

$\Rightarrow\text{L}\times2.5=\frac{22}{7}\times7\times\sqrt{7^2+24^2}$

$\Rightarrow2.5\text{L}=22\times\sqrt{49}+576$

$\therefore\text{L}=\frac{22\times25}{2.5}=220\text{m}$