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The locus of the centre of the circle which bisects the circumferences of the circles `x^2 + y^2 = 4 & x^2 + y^2-2x + 6y + 1 =0` is :A. `2x - 6y - 15 = 0`B. `2x +6y +15 = 0`C. `2x - 6y +15 = 0`D. `2x +6y - 15 = 0` |
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Answer» Correct Answer - A Let required circle be `x^(2) + y^(2) + 2gx +2fy +c =0`. Hence, common chord with `x^(2) + y^(2) -4 =0` is `2gx +2fy +c +4 =0` This is diameter of circle `x^(2) + y^(2) =4` hence `c =-1.` Now, again common chord with other circle is: `2x(g+1) + 2y (f-3) +(c-1) =0` This is diameter of `x^(2) + y^(2) -2x +6y +1 =0`. `:. 2(g+1) -6 (f-3) -5 =0` or `2g - 6f +15 =0` Locus is `2x -6y -15 =0`, which is straight line. |
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