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WAEC Further Mathematics 2008 Question 35

Question 35

Vectors

Find the value of constant k for which a = 4i − kj and b = 3i + 8j are perpendicular.

  1. A.2/3
  2. B.3/2
  3. C.2
  4. D.3
Show the answer and explanation

Answer: B (3/2)

Explanation

Perpendicular vectors have a zero dot product: 12 − 8k = 0, so k = 3/2.