A sector is cut off from a circle radius 8.2cm to form a cone, if the radius of the resulting cone is 3.5cm, calculate the curved surface area of the cone. [take π = 22/7]
-
A.
11.25cm2 -
B.
12.83cm2 -
C.
22.0cm2 -
D.
67.2cm2 -
E.
90.2cm2
Correct Answer: Option E
Explanation
r = 3.5 cm; l = 8.2 cm.
Curved surface area = (pi rl)
= (frac{22}{7} times frac{7}{2} times frac{41}{5})
= 90.2 cm(^2)