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WAEC Further Mathematics 2013 Question 10

Question 10

Coordinate Geometry

Find the equation of the line that is perpendicular to 2y + 5x − 6 = 0 and bisects the line joining the points P(4, 3) and Q(−6, 1).

  1. A.y + 5x + 3 = 0
  2. B.2y − 5x − 9 = 0
  3. C.5y + 2x − 8 = 0
  4. D.5y − 2x − 12 = 0
Show the answer and explanation

Answer: D (5y − 2x − 12 = 0)

Explanation

The given line has gradient −5/2, so the perpendicular has gradient 2/5. Midpoint of PQ is (−1, 2): y − 2 = (2/5)(x + 1), i.e. 5y − 2x − 12 = 0.