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WAEC Further Mathematics 2007 Question 21

Question 21

Statics

A body is acted upon by two forces F1 = (5N, 060°) and F2 = (10N, 180°). Find the magnitude of the resultant force.

  1. A.18.75N
  2. B.15.75N
  3. C.9.50N
  4. D.8.66N
Show the answer and explanation

Answer: D (8.66N)

Explanation

The angle between the forces is 120°. R² = 5² + 10² + 2(5)(10)cos 120° = 125 − 50 = 75, so R = √75 ≈ 8.66 N.