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if `r_(1)` and `r_(2)` are distances of points on the ellipse `5x^(2)+5y^(2)+6xy-8=0` which are at maximum and minimum distance from the origin thenA. `r_(1)+r_(2)=3`B. `|r_(1)-r_(2)|=1`C. `|r_(1)-2r_(2)|=0`D. `r_(1)+2r_(2)=4` |
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Answer» Correct Answer - A::B::C::D Let any point `(rcostheta,rsintheta)` in xy plane We have to maximize & minimize r `5r^(2)cos^(2)theta+5r^(2)sin^(2)theta+6r^(2)sinthetacostheta-8=0` `5r^(2)+3r^(2)sin2theta-8=0` `r^(2)=(8)/(5+3sin2theta)` `r_(max)=2` `r_(min)=1` `r_(1)+r_(2)=3` |
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