The coordinates of the centre of the circle which intersects circles $x^2 + y^2 + 4x + 7 = 0$, $2x^2 + 2y^2 + 3x + 5y + 9 = 0$ and $x^2 + y^2 + y = 0$ orthogonally are
- A. $(-2, 1)$
- B. $(-2, -1)$
- C. $(2, -1)$
- D. $(2, 1)$
✅ Correct Answer: $(-2, -1)$
Explanation
Using the condition for orthogonality $2g_1g_2 + 2f_1f_2 = c_1 + c_2$ for each pair of circles gives the centre as $(-2, -1)$.
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