Question

A tent is of the shape of a right circular cylinder upto a height of $3$ m and then becomes a right circular cone with a maximum height of $13.5$ m above the ground. Calculate the cost of painting the inner side of the tent at the rate of Rs. $2$ per sq m, if the radius of the base is $14$ m.

Answer 1

Surface area to be painted = $\pi rl+2\pi r{h}^1$

= $\pi r(\sqrt{r^2+h^2}+h^1)$

= $\frac{22}{7}\times 14(\sqrt{{14}^2+{10.5}^2}+3)$

= 44 $\times$ 20.5

= ${902m}^2$

Total cost of painting = Rs. $(902\times 2)$

= Rs. $1804$