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WAEC Mathematics 1992 Question 14

Question 14

Mensuration of Solids

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.

  1. A.16/3cm
  2. B.15/3cm
  3. C.16/5cm
  4. D.8/3cm
  5. E.16/10cm
Show the answer and explanation

Answer: A (16/3cm)

Explanation

The arc becomes the base circumference: (240/360) × 2π × 8 = 2πr, so r = (2/3) × 8 = 16/3 cm.