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From the point (-1,2), tangent lines are to the parabola `y^(2)=4x`. If the area of the triangle formed by the chord of contact and the tangents is A, then the value of `A//sqrt(2)` is ___________ . |
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Answer» Correct Answer - 8 (8) The chord of contact w.r.t point O(-1,2) is `y=(x-1)" [Using "yy_(1)=2a(x+x_(1))]` Solving y=x-1 with the parabola, we get the point of intersection as `P(3+2sqrt(2),2+2sqrt(2))andQ(3-2sqrt(2),2-2sqrt(2))` `:." "PQ^(2)=32+32=64` `:." "PQ=8` Also, the length of perpendicular from O(-1,2) on PQ is `4//sqrt(2)`. Then the required area of triangle is `A=(1)/(2)xx8xx((4)/(sqrt(2)))=8sqrt(2)` sq. units |
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