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WAEC Further Mathematics 2017 Question 35

Question 35

Vectors

Find the magnitude and direction of the vector p = (5i − 12j).

  1. A.(13, 113.38°)
  2. B.(13, 067.38°)
  3. C.(13, 025.38°)
  4. D.(13, 157.38°)
Show the answer and explanation

Answer: D ((13, 157.38°))

Explanation

|p| = √(25 + 144) = 13. p points 5 east and 12 south, so its bearing is 90° + tan⁻¹(12/5) = 90° + 67.38° = 157.38°.