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WAEC Further Mathematics 2023 Question 33

Question 33

Coordinate Geometry

Find the radius of the circle 2x2 + 2y2 − 4x + 5y + 1 = 0

  1. A.√5/6
  2. B.5/6
  3. C.33/4
  4. D.√33/4
Show the answer and explanation

Answer: D (√33/4)

Explanation

Divide by 2: x² + y² − 2x + (5/2)y + ½ = 0. Centre (1, −5/4); r² = 1 + 25/16 − ½ = 33/16, so r = √33/4.