Question

If a cylinder is 3m high,is open at top,with base radius 3.5 m then its outer surface area is--------------

Answer 1

$\underline{\pink{ Dimensions \:of \:a \: Cylinder : }}$

$Height (h) = 3 \:cm$

$and \: Base \: radius (r) = 3.5 \:cm$

$\red{ Outer \: surface \:of \:a \: cylinder \:open \:at \:top }$

$= Base \:area + Curved \: surface \:area$

$= \pi r^{2} + 2\pi rh$

$= \pi r( r + 2h )$

$= \frac{22}{7} \times 3.5 ( 3.5 + 2 \times 3 )$

$= 22 \times 0.5 \times ( 3.5 + 6 )$

$= 22 \times 0.5 \times 9.5$

$= 104.5 \:m^{2}$

Therefore.,

$\red{ Outer \: surface \:of \:a \: cylinder \:open \:at \:top }$

$\green { = 104.5 \:m^{2} }$

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