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Consider the family of circles `x^(2)+y^(2)-2x-2ay-8=0` passing through two fixed points A and B . Also, `S=0` is a cricle of this family, the tangent to which at A and B intersect on the line `x+2y+5=0`. The distance between the points A and B , isA. 4B. `4 sqrt(2)`C. 6D. 8 |
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Answer» Correct Answer - 3 We have `x^(2)+y^(2) -2x-2ay-8=0` or `(x^(2)+y^(2)-2x-8)-2ay =0`, which is of the form `S + lambda L =0`. Solving `S -= x^(2)+y^(2) -2x-8=0` and `L -= y =0`, we get `x^(2)-2x-8=0` `implies (x-4) (x+2)=0` `implies x = - 2` or `4` `implies A -= (4,0) , B -= (-2,0)` Distance between A and `B =6` |
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