Q. If distance between directrices of a rectangular hyperbola is 10, then distance between its foci will be
A) $10\sqrt{2}$
B) 5
C) $5\sqrt{2}$
D) 20
Explanation
(d)
Since, distance between directrices, $\frac{2a}{e} = 10$
$\Rightarrow \ a = \frac{10 \times \sqrt{2}}{2} = 5\sqrt{2}$
$\therefore$Distance between foci, $2ae = 2 \times 5\sqrt{2} \times \sqrt{2}$
$= \ 20$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.