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.
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