The diameter of the base of a cone is 6 cm and altitude

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The diameter of the base of a cone is 6 cm and altitude is 4 cm, What is the approximate curved surface area of the cone ?

1. 45 cm²
2. 47 cm²
3. 49 cm²
4. 51 cm²

Correct Option: B

Radius of cone (r) = 6/2 = 3 cm
and height of cone (h) = 4cm
Slant height (l) = √h² + r²
= √(4)² + (3)²
= √16 + 9
= 5 cm
Now, curved surface area = πrl
= (22/7) x 3 x 5
= 330/7 = 47 cm²