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WAEC Mathematics 2009 Question 46

Question 46

Triangles and Quadrilaterals

Find the value of X in the diagram.

Diagram for this question
  1. A.50°
  2. B.60°
  3. C.70°
  4. D.80°
Show the answer and explanation

Answer: D (80°)

Explanation

At the middle vertex the angle between the two arms (on the right) is 360° − 250° = 110°. Split it with the parallel line through the vertex: the lower part is 30° (alternate to the 30°), so the upper part is 80°, and x equals it (alternate angles).