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WAEC Further Mathematics 2006 Question 21

Question 21

Trigonometry

The area of a sector of a circle is 3 cm. If the sector subtends an angle of 1.5 radians at the centre, calculate the radius of the circle.

  1. A.1cm
  2. B.√2cm
  3. C.2cm
  4. D.4cm
Show the answer and explanation

Answer: C (2cm)

Explanation

Area of a sector = ½r²θ, so 3 = ½ × r² × 1.5. Then r² = 4 and r = 2 cm.