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WAEC Further Mathematics 2009 Question 29

Question 29

Vectors

The position vectors of A and B are (2i + j) and (−i + 4j) respectively. Find |AB|.

  1. A.3√2
  2. B.√34
  3. C.√38
  4. D.9√2
Show the answer and explanation

Answer: A (3√2)

Explanation

AB = (−i + 4j) − (2i + j) = −3i + 3j, so |AB| = √(9 + 9) = √18 = 3√2.