Question

Find the curved surface area of a right circular cone of volume=12936cm^3 and base diameter 42cm

Answer 1

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Answer 2

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$\huge\boxed{\red{\bold{Solution}}}$
$<b>$
Given:-
$volume \: of \: cone = 12936cm {}^{3}$
Diameter = 42cm

Radius =D/2=42/2=21cm

$<b>$

$volume \: of \: cone = 1/3 \times \pi \: r {}^{2} h$

12936=1/3πr^2h
12936=1/3π(21×21)×h
12936=21×21×h
12936=462×h
12936/462=h

28cm=h

$slant \: height = \sqrt{h {}^{2} + r {}^{2} } \\l = \sqrt{21 {}^{2} + 28 {}^{2} } \\ l= \sqrt{441 + 784} \\ l= \sqrt{1225 } \\ l = 35 \: cm$
$curve \: surface \: area \: = \pi\: r\:l$
C.S.A=22/7×21×35
C.S.A=22×3×35
C.S.A=2310cm^2

$\huge\underline{\purple{\bold{Thanks}}}$

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