Question

Find the curved surface area of a right circular cone of volume 12936 cm³ and base diameter 42 cm.

Answer 1

Given:

Volume of cone= 12936 cm³

Diameter(d) = 42 cm


Radius(r) = 42/2= 21 cm


Volume of cone= ⅓ π r² h

12936 = (⅓)× (22/7)×( 21×21)× h


12936 = 22× 21× h


h= 12936 / 22×21


h= 6408/11× 21


h= 308/11 = 28 cm


Slant height (l) = √ r²+ h²


l = √ 21²+ 28² = √441+ 784= √ 1225 = 35


l= 35 cm


Curved surface area of cone =πrl


Curved surface area of cone = (22/7) × 21 × 35


Curved surface area of cone =22× 21× 5= 22×105= 2310 cm²


Curved surface area of cone = 2310 cm²


Hence, the Curved surface area of cone = 2310 cm²


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Hope this will help you......