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JAMB Mathematics 1987 Question 33

Question 33

Angles and Polygons

Three angles of a nonagon are equal and the sum of six other angles is 1110°. Calculate the size of one of the equal angles.

  1. A.210°
  2. B.150°
  3. C.105°
  4. D.50°
Show the answer and explanation

Answer: D (50°)

Explanation

The angles of a nonagon add up to (9 − 2) × 180° = 1260°. The three equal angles share 1260° − 1110° = 150°, so each is 50°.