If the chords of contact of tangents from two points (x1,y1) and (x2,y2) to the hyperbola x2a2−y2b2=1 are at right angles, then x1x2y1y2 is equal to
A
−a2b2
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B
−b2a2
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C
−b4a4
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D
−a4b4
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Solution
The correct option is D−a4b4 Equation of chord of contact from (x1,y1) and (x2,y2) to the hyperbola are given by, xx1a2−yy1b2=1 and xx2a2−yy2b2=1 Therefore slopes of these lines are m1=b2a2.x1y1 and m2=b2a2.x2y2 Given both lines are perpendicular ⇒m1⋅m2=−1⇒x1x2y1y2=−a4b4 Hence, option 'D' is correct.