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प्रश्न
If the height of a cylinder becomes `1/4` of the original height and the radius is doubled, then which of the following will be true?
विकल्प
Curved surface area of the cylinder will be doubled.
Curved surface area of the cylinder will remain unchanged.
Curved surface area of the cylinder will be halved.
Curved surface area will be `1/4` of the original curved surface.
उत्तर
Curved surface area of the cylinder will be halved.
Explanation:
Let the new height and radius be `h/4` and 2r respectively, where r and h are original radius and original height respectively of the cylinder.
We know that, curved surface area of cylinder = 2πh
Then, curved surface of the new cylinder
= `2pi(2r) xx 1/4h`
= `4pir xx 1/4h`
= πrh
= `1/2 xx 2pirh` ...[Multiplying and dividing by 2]
= `1/2` original curved surface area
Hence, the curved surface area of the cylinder will be halved.
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