Question

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

Answer 1

Radius of the cap (r) = 7 cm 

Height of the cap (h) = 24 cm 

Slant height of the cap (l) = \(\sqrt{r^2+h^2}\)

= \(\sqrt{7^2+24^2}\)

= \(\sqrt{49+576}\)

= \(\sqrt{625}\)

= 25 

∴ l = 25 cm. 

Lateral surface area of the cap = Cone = πrl 

L.S.A. = 22/7 × 7 × 25 = 550 cm² . 

∴ Area of the sheet required for 10 caps 

= 10 x 550 

= 5500 cm² .