JEE Previous Year Question

A hyperbola, having the transverse axis of length 2 sin θ, is confocal with the ellipse + = 12. Then its equation is

Topic: JEE PYQ

Answer: A. Full step-by-step solution below.

  1. Ax2 cosec2θ – y2 sec2θ = 1
  2. Bx2 sec2θ – y2 cosec2θ = 1
  3. Cx2 sin2θ – y2 cos2θ = 1
  4. Dx2 cos2 θ – y2 sin2θ = 1

Correct answer: A

Solution

(a)For ellipse = 4 ⇒ a = 2, = 3
⇒ = = ⇒ e =
∴ hyperbola is con-focal with ellipse
ae = AE, where 2A = 2sinθ ⇒ 1 = AE ⇒ 1 = (sin θ) E
where E = excentricity of hyperbola
∴ = ( – 1) ⇒ B = cosθ
So equation of hyperbola is
= 1

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