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WAEC Mathematics 2018 Question 43

Question 43

Angles and Polygons

In the diagram, PQ is a straight line. (m + n) = 110°, (n + r) = 130° and (m + r) = 120°. Find the ratio of m : n : r.

Diagram for this question
  1. A.2 : 3 : 4
  2. B.3 : 4 : 5
  3. C.4 : 5 : 6
  4. D.5 : 6 : 7
Show the answer and explanation

Answer: D (5 : 6 : 7)

Explanation

m + n + r = 180° (angles on a line). So r = 70°, m = 50° and n = 60°, giving 50 : 60 : 70 = 5 : 6 : 7.