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Double ordinate `A B`of the parabola `y^2=4a x`subtends an angle `pi/2`at the focus of the parabola. Then the tangents drawn to the parabolaat `Aa n dB`will intersect at`(-4a ,0)`(b) `(-2a ,0)``(-3a ,0)`(d) none of theseA. (-4a,0)B. (-2a,0)C. (-3a,0)D. none of these |
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Answer» Correct Answer - A (1) Let `A-=(at^(2),2at),B-=(at^(2),-2at)`. Then `m_(OA)=(2)/(t),m_(OB)=(-2)/(t)` Thus, `((2)/(t))((-2)/(t))=-1` `or" "t^(2)=4` Thus, the tangents will intersect at (-4a,0). |
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