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OAU Post-UTME Mathematics 2021 (Batch B) Question 15

Question 15

Coordinate Geometry

Find the equation of the circle which has its centre at (−2, 3) and passes through the point (4, 5).

  1. A.x2 + 2x + y2 − 3y − 27 = 0
  2. B.x2 + y2 + 4x − 6y − 27 = 0
  3. C.x2 + y2 − 4x + 6y + 27 = 0
  4. D.x2 + y2 − 2x + 3y − 27 = 0
Show the answer and explanation

Answer: B (x2 + y2 + 4x − 6y − 27 = 0)

Explanation

r² = 6² + 2² = 40. (x + 2)² + (y − 3)² = 40 expands to x² + y² + 4x − 6y − 27 = 0.