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JAMB Mathematics 1992 Question 35

Question 35

Trigonometry

In the fig. above, if XZ is 10cm, calculate RY in cm

Diagram for this question
  1. A.10
  2. B.10(1 − 1/√3)
  3. C.10(1 − √3)
  4. D.10(1 − 1/√2)
Show the answer and explanation

Answer: B (10(1 − 1/√3))

Explanation

Angle YXZ = 30° + 15° = 45°, so YZ = 10 tan 45° = 10. RZ = 10 tan 30° = 10/√3. RY = 10 − 10/√3 = 10(1 − 1/√3).