Mathematics

A sector is cut off from a circle radius 8.2cm to form a cone, if…

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)