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WAEC Further Mathematics 2016 Question 35

Question 35

Vectors

Given that r = 3i + 4j and t = −5i + 12j, find the acute angle between them.

  1. A.14.3°
  2. B.55.9°
  3. C.59.5°
  4. D.75.6°
Show the answer and explanation

Answer: C (59.5°)

Explanation

r·t = −15 + 48 = 33; |r| = 5, |t| = 13. cos θ = 33/65, θ ≈ 59.5°.