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प्रश्न
The internal and external diameters of a hollow hemi-spherical vessel are 21 cm and 28 cm respectively. Find: external curved surface area .
उत्तर
External radius (R) = 14 cm
Internal radius (r) =`21/2` cm
External curved surface area =
`2piR^2`
=`2xx22/7xx14xx14`
=`1232 "cm"^2`
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