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The radius of a right circular cone is 7...

The radius of a right circular cone is 7 cm at its vertical angle is `60^@`. Find the curved surface area of the cone.

Text Solution

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The semi - vertical angle is `(60^@)/(2)=30^@`.
Now , from the right - angled `DeltaAOB` we get,
`(AB)/(OB)=cosec30^@ or , (AB)/(7)=2 [because OB="radius" =7 cm and cosec 30^@=2]`
or `AB=14`.
`therefore` the height of the cone `=14cm`.
`therefore` the curved surface area of the cone `=(22)/(7)xx7xx14sq-cm=308sq-cm`.
Hence , the curved surface area of the cone `=308`sq-cm.
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