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JAMB Mathematics 1986 Question 39

Question 39

Trigonometry

In ΔXYZ above, determine the cosine of angle Z

Diagram for this question
  1. A.3/4
  2. B.29/36
  3. C.2/3
  4. D.1/2
Show the answer and explanation

Answer: B (29/36)

Explanation

The sides next to Z are XZ = 3 and YZ = 6, and the side opposite is XY = 4. cos Z = (3² + 6² − 4²)/(2 × 3 × 6) = 29/36.