Question

find the curved surface area of a right circular cone of volume 12936 cm cube and base diameter 42 CM.

Answer 1

hey!!!

given diameter of the base of the circular cone = 42cm

therefore it's radius = 42/2 = 21cm

volume of the circular cone = 12936cm³
>> 1/3πr²h = 12936cm³
>> 1/3×22/7×21×21×h = 12936cm³
>> 22/3×3×21×h = 12936cm³
>> 22×21×h = 12936cm³
>> 462×h = 12936cm³
>> h = 12936/462
>> h = 28cm

the height of the circular cone is 28cm.

now, we have to find it's Length (slant height) to find the CSA of the circular cone.

l = √(r²+h²)

l = √(21²+28²)

l = √(441+784)

l = √1225

l = 35

therefore, the slant height (l) of the circular cone is 35cm.

CSA of the circular cone = πrl
= 22/7×21×35
= 22×3×35
= 2310cm²

cheers!!!