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WAEC Mathematics 2013 Question 39

Question 39

Angles and Polygons

In the diagram, PQ is a straight line. Calculate the value of the angle labelled 2y.

Diagram for this question
  1. A.130°
  2. B.120°
  3. C.110°
  4. D.100°
Show the answer and explanation

Answer: D (100°)

Explanation

Below PQ: 80° + 50° + (x + 10)° = 180°, so x = 40. Above PQ: 2y + 2x = 180°, so 2y = 180° − 80° = 100°.