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?

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