A joker’s cap is in the form of a right circular cone of base radius 7 cm and height 24 cm.
Question:

A joker’s cap is in the form of a right circular cone of base radius 7 cm and height 24 cm. Find the area of the sheet required to make 10 such caps.

Solution:

Given that,

Radius of conical cap(r) = 7 cm

Height of the conical cap (h) = 24 cm

Slant height (l) of conical cap

$=\sqrt{\mathrm{r}^{2}+\mathrm{h}^{2}}$

$=\sqrt{7^{2}+24^{2}}$

= 25 cm

C.S.A of 1 conical cap = πrl

= 22/7 ∗ 7 ∗ 25

$=550 \mathrm{~cm}^{2}$

Curved surface area of 0 such conical caps $=5500 \mathrm{~cm}^{2}$

Thus, $5500 \mathrm{~cm}^{2}$ sheet will be required for making 10 caps.