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WAEC Mathematics 2011 Question 19

Question 19

Mensuration of Plane Shapes

The perimeter of a sector of a circle of radius 4 cm is (π + 8) cm. Calculate the angle of the sector.

  1. A.45°
  2. B.60°
  3. C.75°
  4. D.90°
Show the answer and explanation

Answer: A (45°)

Explanation

Perimeter = arc + 2 × 4, so the arc is π cm. θ/360 × 2π × 4 = π gives θ = 45°.