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WAEC Further Mathematics 2021 Question 20

Question 20

Vectors

In ΔPQR, PQ = 5i − 2j and QR = 4i + 3j. Find RP.

  1. A.−i − 5j
  2. B.−9i − j
  3. C.i + 5j
  4. D.−9i + j
Show the answer and explanation

Answer: B (−9i − j)

Explanation

Going round the triangle, PQ + QR + RP = 0, so RP = −(5i − 2j) − (4i + 3j) = −9i − j.