AIEEE 2006 (Offline)Question 1
In the ellipse, the distance between its foci is $6$ and minor axis is $8$. Then its eccentricity is :
Ellipse
Solution
Formulas used. (1) $a^2=b^2+c^2$, $e=\frac ca$Step 1 - Data. $2c=6\Rightarrow c=3$; $2b=8\Rightarrow b=4$. Step 2 - Use (1). $a=\sqrt{16+9}=5$, $e=\frac35$. Answer: A