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JAMB Mathematics 2013 Question 24

Question 24

Triangles and Quadrilaterals

In the diagram above, find the value of x.

Diagram for this question
  1. A.45°
  2. B.15°
  3. C.30°
  4. D.40°
Show the answer and explanation

Answer: D (40°)

Explanation

The marked equal sides make the small triangle isosceles, so both its base angles are 15° and its exterior angle is 30°. In the big triangle, x = 180° − 110° − 30° = 40°.