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WAEC Mathematics 2009 Question 23

Question 23

Triangles and Quadrilaterals

Find the value of x in the diagram.

Diagram for this question
  1. A.50°
  2. B.30°
  3. C.22°
  4. D.17°
Show the answer and explanation

Answer: D (17°)

Explanation

The marked angles are the exterior angles of the polygon, which add to 360°: (x + 64) + 2x + (3x − 54) + 5x + 4x + 3x + (2x + 10) = 20x + 20 = 360, so x = 17.