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JAMB Mathematics 1989 Question 34

Question 34

Angles and Polygons

If PST is a straight line and PQ = QS = SR in the above diagram, find y.

Diagram for this question
  1. A.24°
  2. B.48°
  3. C.72°
  4. D.84°
Show the answer and explanation

Answer: C (72°)

Explanation

PQ = QS gives angle QSP = 24°, and the exterior angle SQR = 24° + 24° = 48°. SQ = SR gives angle SRQ = 48°, so angle QSR = 84°. On the straight line at S, y = 180° − 24° − 84° = 72°.