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If the chord `xcosalpha+ysinalpha=p`of the hyperbola `(x^2)/(16)-(y^2)/(18)=1`subtends a right angle at the center, and the diameter of the circle,concentric with the hyperbola, to which the given chord is a tangent is `d ,`then the value of `d/4`is__________ |
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Answer» Correct Answer - 24 The equation of hyperbola is `(x^(2))/(16)-(y^(2))/(18)=1` `"or "9x^(2)-8y^(2)-144=0` Homogenizing this equation using `(x cosalpha+y sin alpha)/(p)=1` We have `9x^(2)-8y^(2)-144((x cos alpha+y sin alpha)/(p))^(2)=0` Since these lines are perpendicular to each other, we have `9p^(2)-8p^(2)-144(cos^(2)alpha+sin^(2)alpha)=0` `p^(2)=144or p = pm12` `therefore" Radius of circle"=12` `therefore" Diameter of circle"=24` |
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