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Let `P(alpha,beta)` be a point in the first quadrant. Circles are drawn through P touching the coordinate axes. Equation of common chord of two circles isA. `x +y = alpha - beta`B. `x +y = 2 sqrt(alpha beta)`C. `x +y = alpha +beta`D. `alpha^(2) -beta^(2) = 4 alpha beta` |
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Answer» Correct Answer - C `S_(1) = x^(2) +y^(2) - 2r_(i)(x+y) +r_(i)^(2) =0`, where `i =1,2` Thus, equation of common chord. `2(r_(2)-r_(1)) (r+y) +r_(1)^(2) -r_(2)^(2) =0` `rArr 2(x+y) = (r_(1)+r_(2)) = 2 (alpha + beta)` `rArr x +y = alpha + beta`. |
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