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JAMB Mathematics 1997 Question 36

Question 36

Trigonometry

In a triangle XYZ, if ∠XYZ is 60°, XY = 3cm and YZ = 4cm. Calculate the length of the side XZ.

  1. A.√23cm
  2. B.√13cm
  3. C.2√5cm
  4. D.2√3cm
Show the answer and explanation

Answer: B (√13cm)

Explanation

By the cosine rule, XZ² = 3² + 4² − 2(3)(4)cos 60° = 25 − 12 = 13, so XZ = √13 cm.