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 \pi = 22/7]
A
11.25cm2
B
12.83cm2
C
22.0cm2
D
67.2cm2
E
90.2cm2
Verified Correct Answer: E.
Step-by-Step Mathematical Solution
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\(^2\)
Source: Myschool Past Questions Archive (Record #22411)