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WAEC Further Mathematics 2013 Question 19

Question 19

Trigonometry

The angle subtended by an arc of a circle at the centre is π/3 radians. If the radius of the circle is 12 cm, calculate the perimeter of the major sector.

  1. A.4(6 + 5π)
  2. B.4(6 + 2π)
  3. C.4(3 + 3π)
  4. D.4(3 + 5π)
Show the answer and explanation

Answer: A (4(6 + 5π))

Explanation

The major sector angle is 2π − π/3 = 5π/3. Perimeter = 2(12) + 12(5π/3) = 24 + 20π = 4(6 + 5π).