InterviewSolution
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InterviewSolution
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Filnd the distance between the directricesthe ellipse `(x^2)/(36)+(y^2)/(20)=1.` |
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Answer» The equation of ellipse is `(x^(2))/36+(y^(2))/20=1` On comparing this equation with `(x^(2))/(a^(2))+(y^(2))/(b^(2))=1`we get `a=6,b=2sqrt5` we know that, `b^(2)=a^(2)(1-e^(2))` ltbr. `rArr 20=36(1-e^(2))` `rArr 20/36=1-e^(2)` `therefore e=sqrt(1-20/36)=sqrt(16/36)` `E=4/6=2/3` Now, directrices=`(+a/e,-1//e)` `therefore a/e=(6/2)/3=(6xx3)/2=9` and `-a/e=-9` `therefore` Distance between the directrices=`abs(9-(-9))=18` |
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