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WAEC Mathematics 2015 Question 46

Question 46

Angles and Polygons

Two angles of a pentagon are in the ratio 2:3. The others are 60° each. Calculate the smaller of the two angles.

  1. A.72°
  2. B.100°
  3. C.120°
  4. D.144°
Show the answer and explanation

Answer: D (144°)

Explanation

Angles of a pentagon add to 540°. 540° − 3 × 60° = 360°, shared 2:3 gives 144° and 216°; the smaller is 144°.