Consider the ellipse x 2 4 + y 2 3 = 1 . Let H α , 0 , 0 < α < 2 , be a point. A straight…

Consider the ellipse x24+y23=1. Let Hα,0,0<α<2, be a point. A straight line drawn through H parallel to the y-axis crosses the ellipse and its auxiliary circle at points E and F respectively, in the first quadrant. The tangent to the ellipse at the point E intersects the positive x-axis at a point G. Suppose the straight line joining F and the origin makes an angle ϕ with the positive x-axis.

  List-I   List-II
I If ϕ=π4, then the area of the triangle FGH is P 3-148
II If ϕ=π3, then the area of the triangle FGH is Q 1
III If ϕ=π6, then the area of the triangle FGH is R 34
IV If ϕ=π12, then the area of the triangle FGH is S 123
    T 332

The correct option is:

  1. IR; IIS;IIIQ;IVP
  2. IR; IIT;IIIS;IVP
  3. IQ; IIT;IIIS;IVP
  4. IQ; IIS;IIIQ;IVP

Solution

Given x24+y23=1

Let α2cosϕ

Tangent at E2cosϕ,3sinϕ to the ellipse is  xcosϕ2+ysinϕ3=1

This intersect x-axis at G2secϕ,0

Drawing the figure as per the information, we get, 

Area of triangle FGH=122secϕ-2cosϕ2sinϕ

Δ=2sin2ϕ.tanϕ

Δ=1-cos2ϕ·tanϕ

I.  If ϕ=π4,Δ=1Q

II. If ϕ=π3,Δ=2·322·3=332T

III.  If ϕ=π6,Δ=2·122·13=123S

IV.  If ϕ=π12,Δ=1-32·2-3=2-322=3-148P

Asked in: JEE Advanced 2022 (Paper 1)

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