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If angle between asymptotes of hyperbola x2/a2 - y2/b2 = 1 is 120° and product of perpendiculars drown from foci upon its any tangent is 9, then locus of point of intersection of perpendicular tangents of the hyperbola can be(a) x2 + y2 = 18(b) x2 + y2 = 6(c) x2 + y2 = 9(d) x2 + y2 = 3 |
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Answer» Correct option (a) x2 + y2 = 18 Explanation: 2tan–1 b/a = 60° b/a = 1/√3 b2 = 9 ∴ a2 = 27 Required locus is director circle i.e x2 + y2 = 27 – 9 x2 + y2 = 18 If b/a = tan 60° = √3 a2 = 3 Then equation of director circle is x2 + y2 = 3 - 9 = -6 which is not possible. |
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