Gujarati
Hindi
10-2. Parabola, Ellipse, Hyperbola
normal

In an ellipse, the distance between its foci is $6$ and minor axis is $8.$ Then its eccentricity is :

A

$\frac{3}{5}$

B

$\frac{1}{2}$

C

$\frac{4}{5}$

D

$\frac{1}{\sqrt 5}$

Solution

$2 \mathrm{ae}=6 \Rightarrow \mathrm{ae}=3$

Minor axis $=2 b=8 \Rightarrow b=4$

As, $b^{2}=a^{2}\left(1-e^{2}\right) \Rightarrow 16=a^{2}-a^{2} e^{2}$

$\Rightarrow 16=a^{2}-9$

$\Rightarrow \mathrm{a}^{2}=25 \Rightarrow \mathrm{a}=5$

ae $=3 \Rightarrow \mathrm{e}=\frac{3}{5}$

Standard 11
Mathematics

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