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If the circles `x^2+y^2-9=0`and `x^2+y^2+2a x+2y+1=0`touch each other, then `alpha`is`-4/3`(b) 0(c) 1 (d)`4/3`A. `-4//3`B. 0C. 1D. `4//3` |
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Answer» Correct Answer - 1,4 The equation of the radical axis is `2 alpha x +2y+10=0` i.e., `alpha x +y+5=0` (i) Putting the value of y from (i) in the circle `x^(2)+y^(2)=9`, we get `(1+alpha^(2))x^(2)+10 alpha x +16 =0` Radical axis is trangent . So, `D=0` or `36alpha^(2)-64=0` or `alpha = +- (4)/(3)` |
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