1.

An ellipse has eccentricity \[\frac{1}{2}\] and one focus at the point\[P\left( \frac{1}{2},\ 1 \right)\]. Its one directrix is the common tangent nearer to the point P, to the circle \[{{x}^{2}}+{{y}^{2}}=1\] and the hyperbola\[{{x}^{2}}-{{y}^{2}}=1\]. The equation of the ellipse in the standard form, is       [IIT 1996]

A.            \[\frac{{{(x-1/3)}^{2}}}{1/9}+\frac{{{(y-1)}^{2}}}{1/12}=1\]
B.            \[\frac{{{(x-1/3)}^{2}}}{1/9}+\frac{{{(y+1)}^{2}}}{1/12}=1\]
C.            \[\frac{{{(x-1/3)}^{2}}}{1/9}-\frac{{{(y-1)}^{2}}}{1/12}=1\]
D.            \[\frac{{{(x-1/3)}^{2}}}{1/9}-\frac{{{(y+1)}^{2}}}{1/12}=1\]
Answer» B.            \[\frac{{{(x-1/3)}^{2}}}{1/9}+\frac{{{(y+1)}^{2}}}{1/12}=1\]


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