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If radii of director circles of `x^2/a^2+y^2/b^2=1 and x^2/a^2-y^2/b^2=1` are `2r and r` respectively, let `e_E and e_H` are the eccentricities of ellipse and hyperbola respectively, thenA. `2e_(h)^(2)-e_(e)^(2)=6`B. `e_(e)^(2)-4e_(h)^(2)=6`C. `4e_(h)^(2)-e_(e)^(2)=6`D. none of these |
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Answer» The equation of the director circles of ellipse and hyperbola are `x^(2)+y^(2)=a^(2)+b^(2)` and `x^(2)+y^(2)=a^(2)-b_(1)^(2)` respectively. `:.2r=sqrt(a^(2)+b^(2))` and `r=sqrt(a^(2)-b_(1)^(2))` `=2sqrt(a^(2)-b_(1)^(2))=sqrt(a^(2)+b^(2))` `implies4(a_(1)^(2)-b_(1)^(2))=a^(2)+b^(2)` `implies4(1-(b_(1)^(2))/(a^(2)))=(1+(b^(2))/(a^(2)))` `implies4{1-(e_(h)^(2)-1){=1+(1-e_(e)^(2))` `implies8-4e_(h)^(2)=2-e_(e)^(2)implies4e_(h)^(2)-e_(e)^(2)=6` |
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