Question

If the centre, one of the foci and semi-major axis of an ellipse be (0, 0), (0, 3) and 5 then its equation is-

• A. $\frac{x^{2}}{16}$+ $\frac{y^{2}}{25}$= 1
• B. $\frac{x^{2}}{25}$+ $\frac{y^{2}}{16}$= 1
• C. $\frac{x^{2}}{9}$+ $\frac{y^{2}}{25}$= 1
• D. None of these

Answer 1

Answer: (B)

$\frac{x^{2}}{25}$+ $\frac{y^{2}}{16}$= 1

Answer 2

Centre (0,0); Focus S(0, 3) ̃ BB¢ = 2b ̃ b = 5

Q CS = be = 3 ̃ e = 3/5;

\ a² = b²(1 – e²) =16

Hence, required equation = $\frac{x^{2}}{25}$+ $\frac{y^{2}}{16}$= 1