A joker’s cap is in the form of a right- circular cone whose base radius is 7 cm and height is 24 cm. The area of the sheet required
A joker’s cap is in the form of a right- circular cone whose base radius is 7 cm and height is 24 cm. The area of the sheet required to make 10 such caps is
A) 550 cm2
B) 5500 cm2
C) 55000 cm2
D) None
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Correct option is: B) 5500 cm2
We have r = 7 cm and h = 24 cm.
Area of sheet required to make 1 joker's cap
= \(\pi rl = \pi r\sqrt {r^2+h^2}\) (\(\because\) l = \(\sqrt {r^2+h^2}\)))
= \(\frac {22}7 \times 7\sqrt {7^2+24^2}\)
= \(22\sqrt{49+576} = 22\sqrt{625} = 22 \times 25 = 550 cm^2\)
\(\therefore\) Area of sheet required to make 10 such caps = 550 \(\times\) 10 \(cm^2\)= 5500 \(cm^2\).
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