Question

A solid cylinder has total surface area 462cmcube.Its curved surface area is one third of its total surface.Find its radius its height its volume .

Answer 1

given,

TSA = 462cm²

=> 2πr(r+h) = 462

=> 2*22/7*r(r+h)=462

=> r(r+h)=21*7/2

=> r²+rh=21*7/2=147/2..................(1)

CSA = 1/3 (462)

=> 2πrh=154cm²

=> 2*22/7*rh=154

=> rh=7*7/2=49/2.........................(2)

substitute (2) in (1)

=> r²+49/2=147/2

=> r²=147/2 - 49/2

=> r²=147-49/2

=> r²=98/2=49

=> r²=7²

=> r=7cm

substitute r=7cm in (2)

=> rh=49/2

=> 7*h=49/2

=> h=7/2cm

Volume = πr²h

= 22/7 * 7² * 7/2

= 49 * 11

= 539cm³

HOPE U UNDERSTAND

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