Q. The ellipse $\frac{x^{2}}{25} + \frac{y^{2}}{16} = 1$ and the hyperbola $\frac{x^{2}}{25} - \frac{y^{2}}{16} = 1\$ have in common

A) centre only
B) Centre, foci and directrices
C) Centre, foci and vertices
D) Centre and vertices only
Explanation

(d)
Let $e$ and $e’$ be the eccentricities of the ellipse and hyperbola
$\therefore e = \sqrt{\frac{{a^{2} - \ b}^{2}}{a^{2}}} = \ \sqrt{\frac{25 - 16}{25}} = \frac{3}{5}$
and$\ \ e’ = \sqrt{\frac{{a^{2} + b}^{2}}{a^{2}}} = \sqrt{\frac{25 + 16}{25}\ } = \frac{\sqrt{41}}{5}$
Centre of ellipse is (0, 0) and centre of hyperbola is (0, 0)
Foci of ellipse are $( \pm ae,0)$ or $( \pm 3,0)$ foci of hyperbola are ($\pm ae^{'},0)$ or $\left( \pm \sqrt{41},\ 0 \right)$
Directrices of ellipse are $x = \pm \frac{a}{e} \Rightarrow x = \pm \frac{25}{3}$
Directrices of hyperbola are $x = \pm \frac{a}{e}$
$\Rightarrow \ x = \pm \frac{25}{\sqrt{41}}$
Vertices of ellipse are $( \pm a,0)$ or $( \pm 5,0)$
Vertices of hyperbola are $( \pm a,0)$ or $( \pm 5,0)$
From the above discussions, their are common in centre and vertices.

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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