Q97 / 160 · AP EAMCET 2019 (21 Apr Shift 2) · Mathematics

If tangents are drawn to the ellipse x29+y25=1 at the ends of latus recta, then the area of the quadrilateral thus formed is

  • Correct answer
    A
    27 sq. units
  • B
    154 sq. units
     
  • C
    132 sq. units
  • D
    45 sq. units

Solution

The given equation of the ellipse is,

x29+y25=1

The eccentricity of the ellipse is,

e=1-59=23

The coordinates of the endpoints of latus rectum are

L2,53,M-2,53,M'-2,-53 and L'2,-53

The equations of tangents at these points are,

2 x+3 y-9=0
-2 x+3 y-9=0
2 x+3 y+9=0
-2 x+3 y+9=0

Figure

By solving the above equations,

A0,3

B-92,0

C0,-3
D92,0

And
AC=(3+3)2=6

BD=92+922=9

The area of the quadrilateral is,
A=12×9×6

=27 sq.units

Hence, the correct answer is option: 'A'.

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