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WAEC Mathematics 2009 Question 39

Question 39

Angles and Polygons

Each of the interior angles of a regular polygon is 140°. Calculate the sum of all the interior angles of the polygon.

  1. A.1080°
  2. B.1260°
  3. C.1800°
  4. D.2160°
Show the answer and explanation

Answer: B (1260°)

Explanation

Each exterior angle is 40°, so n = 360/40 = 9 sides. Sum = 9 × 140° = 1260°.