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प्रश्न
The volume of a cylinder of height 8cm is 392π cm3. Find its lateral surface area and its total surface area.
उत्तर
Height (h) = 8cm
Let r be the radius of the cylinder.
Volume of cylinder = 392π cm3
i.e., πr2h = 392π
r2 x 8 = 392
r2 = 49
r = `sqrt(49)`
r = 7cm
Now,
L.S.A. of cylinder
= 2 x π x r x h
= `2 xx (22)/(7) xx 7xx 8`
= 352cm2
T.S.A. of cylinder
= (2 x π x r x h) + (2 x π x r2)
= `(2 xx (22)/(7) xx 7 xx 8) + (2 xx (22)/(7) xx 7^2)`
= 352 + 308
= 660cm2.
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