Question

A 5-m-wide cloth is used to make a conical tent of base diameter 14 m and height 24 m. Find the cost of cloth used at the rate of ₹25 per metre.

Answer 1

We have, 

the height of the cone, h = 24 m, the base diameter of the cone, `r = d/2 = 14/2 = 7 m`

Also, the base radius of the cone, `l = sqrt(h^2 + r^2)`

`= sqrt(24^2 + 7^2)`

`= sqrt(576 + 49)`

`=sqrt(625)`

`=25 m`

The curved surface area of the tent = `pirl`

`= 22/7xx 7xx25`

= 550 m²  

⇒ The area of cloth requried to make the tent = 550 m²

⇒ The length of the cloth = `550/5 = 110  m`

So, the cost of cloth used = 110 ×25 = ₹2750