MCQ
A point ratio of whose distance from a fixed point and line $x = 9/2$ is always $2 : 3$. Then locus of the point will be
- AHyperbola
- ✓Ellipse
- CParabola
- DCircle
Focus $S( - 2,\,0)$,
Equation of directrix $2x - 9 = 0$
${(PS)^2} = \frac{4}{9}{(PM)^2}$
==> ${(h + 2)^2} + {(k)^2} = \frac{4}{9}{\left( {\frac{{2h - 9}}{2}} \right)^2}$
==> $9[{(h + 2)^2} + {(k)^2}] = \frac{{4{{(2h - 9)}^2}}}{4}$
==> $9{h^2} + 9{k^2} + 36h + 36 = 4{h^2} + 81 + 36h$
==> $\frac{{5{h^2}}}{{45}} + \frac{{9{k^2}}}{{45}} = 1$
==> $\frac{{{h^2}}}{9} + \frac{{{k^2}}}{5} = 1$
Locus of point $P(h, k)$ is $\frac{{{x^2}}}{9} + \frac{{{y^2}}}{5} = 1$, which is an ellipse
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