Q19 / 51 · JEE Advanced 2023 (Paper 1) · Mathematics

Let T1 and T2 be two distinct common tangents to the ellipse E:x26+y23=1 and the parabola P:y2=12x. Suppose that the tangent T1 touches P and E at the points A1 and A2, respectively and the tangent T2 touches P and E at the points A4 and A3, respectively. Then which of the following statements is(are) true?

  • Correct answer
    A
    The area of the quadrilateral A1A2A3A4 is 35 square units
  • B
    The area of the quadrilateral A1A2A3A4 is 36 square units
  • Correct answer
    C
    The tangents T1 and T2 meet the x-axis at the point –3, 0
  • D
    The tangents T1 and T2 meet the x-axis at the point –6, 0

Solution

Given,

Equation of ellipse

E:x26+y23=1,

Now equation of tangent with slope m1 will be :

T1: y=m1x±6m12+3

And equation of parabola,

P:y2=12x,

So, equation of tangent with slope m2 will be:

y=m2x+3m2

Now for common tangent

m=m1=m2, ±6m12+3=3m2

⇒ m=±1

Hence, equation of common tangents will be,

y=x+3 and y=–x-3

Now we know that,

Point of contact for parabola is am2, 2am

⇒ A1≡3, 6, A43-6

Now let A2x1, y1

So, equation of tangent to ellipse E at point A2x1, y1 is given by,

 xx16+yy13=1

Now comparing above equation with y=x+3,

We get, -x16=y13=13

⇒A2≡-63,33≡-2,1

Now A3 is mirror image of A2 in x-axis 

⇒A3-2, -1 

Figure

Now finding the intersection point of T1=0 and T2=0, we get -3, 0

So, Area of quadrilateral A1A2A3A4=1212+2×5=35 square units

Hence, the correct answer is options: 'A', 'C'.

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