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10-2. Parabola, Ellipse, Hyperbola
easy
If the latus rectum of an ellipse be equal to half of its minor axis, then its eccentricity is
A
$3/2$
B
$\sqrt 3 /2$
C
$2/3$
D
$\sqrt 2 /3$
Solution
(b) $\frac{{2{b^2}}}{a} = b$
==> $\frac{b}{a} = \frac{1}{2}$
==> $\frac{{{b^2}}}{{{a^2}}} = \frac{1}{4}$
Hence $e = \sqrt {1 – \frac{{{b^2}}}{{{a^2}}}} $
$= \frac{{\sqrt 3 }}{2}$.
Standard 11
Mathematics