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WAEC Mathematics 2016 Question 20

Question 20

Circle Theorems

In the diagram, O, is the centre of circle, ∠XOZ = (10m)° and ∠XWZ = m°. Calculate the value of m.

Diagram for this question
  1. A.30
  2. B.36
  3. C.40
  4. D.72
Show the answer and explanation

Answer: A (30)

Explanation

∠XWZ = m stands on the arc XYZ, so the angle at the centre on that arc is 2m. The two angles at O add to 360°: 10m + 2m = 360, so m = 30.