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A rectangular strip 25 cm xx 7cm is rota...

A rectangular strip `25 cm xx 7cm` is rotated about the longer side. Find the total surface area of the solid thus generated.

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rectangular strip is rotated about the longer side so it looks like a cylinder
whose radius is 7 cm
and height `=25cm`
so total surface area of this solid cylinder `=2xxpixxr^2+2xxpixxrxxh`
`=2xxpixx7^2+2xxpixx7xx25`
`=1408cm^2`
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