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A point moves so that its distance from the point (2,0) is always (1)/(3)` of its distances from the line x-18. If the locus of the points is a conic, then length of its latus rectum isA. `(16)/(3)`B. `(32)/(3)`C. `(8)/(3)`D. `(15)/(4)` |
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Answer» Clearly, locus is ellipse with eccetntircity `e=(1)/(3)`. Hence, focus is (2,0) and directrixd is x-18=0 Distance of focus from directrix=16 `rArra//e-ae=16` `:.(8)/(3)a=16` `:.a=6` `:. b^(2)=a^(2)(1-e^(2))=36(1-1//9)=32` `:. L.R.=(2b^(2))/(A)=(32)/(3)` |
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