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WAEC Further Mathematics 2013 Question 40

Question 40

Statics

A body is kept at rest by three forces F1 = (10N, 030°), F2 = (10N, 150°) and F3. Find F3.

  1. A.(12N, 090°)
  2. B.(10 N, 270°)
  3. C.(10 N, 180°)
  4. D.(10N, 120°)
Show the answer and explanation

Answer: B ((10 N, 270°))

Explanation

F₃ must equal −(F₁ + F₂). As bearings, F₁ + F₂ = 10 N due east, so F₃ = (10 N, 270°). (Measuring angles from the x-axis instead, F₁ + F₂ = 10 N at 90° and F₃ is again at 270°.)