The angle of a sector of a circle of radius 8cm is 240°. This sector is bent to form a cone. Find the radius of the base of the cone.

  • A 16/3cm
  • B 15/3cm
  • C 16/5cm
  • D 8/3cm
  • E 16/10cm
waec 1992mathematics

The correct answer is A. 16/3cm

L = θ/360 x 2πR = 240/360 x 2 x 22/7 x 8/1 ... (1)

This must be equal to the circumference of the circle which is 2πr = 44R/7 .... (2)

equate (1) and (2)

r = 16/3 = 51/3

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