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WAEC Mathematics 2011 Question 10

Question 10

Triangles and Quadrilaterals

Find the size of the angle marked x in the diagram.

Diagram for this question
  1. A.108°
  2. B.112°
  3. C.128°
  4. D.142°
Show the answer and explanation

Answer: C (128°)

Explanation

Both slanting lines are perpendicular to the same line, so they are parallel. The slanting line makes 52° with the crossing line at the bottom, so it makes 52° with it at the top (alternate angles). x is on a straight line with that angle: x = 180° − 52° = 128°.