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WAEC Further Mathematics 2009 Question 12

Question 12

Trigonometry

An arc of length 10.8cm subtends an angle of 1.2 radians at the centre of a circle. Calculate the radius of the circle.

  1. A.12.6cm
  2. B.12.0cm
  3. C.9.6cm
  4. D.9.0cm
Show the answer and explanation

Answer: D (9.0cm)

Explanation

Arc length l = rθ, so r = 10.8 ÷ 1.2 = 9.0 cm.