Conic Sections Question 476

Question: The equation to the hyperbola having its eccentricity 2 and the distance between its foci is 8

[Karnataka CET 2005]

Options:

A) $ \frac{x^{2}}{12}-\frac{y^{2}}{4}=1 $

B) $ \frac{x^{2}}{4}-\frac{y^{2}}{12}=1 $

C) $ \frac{x^{2}}{8}-\frac{y^{2}}{2}=1 $

D) $ \frac{x^{2}}{16}-\frac{y^{2}}{9}=1 $

Show Answer

Answer:

Correct Answer: B

Solution:

Distance between foci = 8 $ 2ae=8 $ also $ e=2 $ ; $ 2a=4 $

therefore $ a=2 $

therefore $ a^{2}=4 $ ;$ b^{2}=4(4-1)=12 $

Equation of hyperbola is $ \frac{x^{2}}{4}-\frac{y^{2}}{12}=1 $ .