Q: If e and e1 are the eccentricities of the hyperbola xy = c2 and x2 – y2 = c2, then e2 + e12 is equal to
(A) 1
(B) 4
(C) 6
(D) 8
Click to See Answer :
Ans: (B)
Sol: e = √2 , e1 = √2
⇒ e2 + e12 = 4.
Hence (B) is the correct answer.
Hyperbola
Co-ordinate Geometry
The eccentricity of conic 9x^2 – 16y^2 = 144 is
Q: The eccentricity of conic 9x2 – 16y2 = 144 is
(A) 4/5
(B) 5/4
(C) 4/3
(D) √7
Click to See Answer :
Ans: (B)
Sol: Hyperbola is $\large \frac{x^2}{16} – \frac{y^2}{9} = 1$
b2 = a2(e2 – 1)
⇒ 9 = 16(e2 – 1)
⇒ e = 5/4