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WAEC Further Mathematics 2023 Question 26

Question 26

Vectors

Calculate, correct to one decimal place, the angle between 5i + 12j and −2i + 3j.

  1. A.54.8°
  2. B.56.3°
  3. C.66.4°
  4. D.76.3°
Show the answer and explanation

Answer: B (56.3°)

Explanation

Dot product = −10 + 36 = 26; magnitudes 13 and √13. cos θ = 26/(13√13) ≈ 0.5547, so θ ≈ 56.3°.