If tangents are drawn to the ellipse x 2 9 + y 2 5 = 1 at the ends of latus recta, then the area of the…

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
  1. 27 sq. units
  2. 154 sq. units
     
  3. 132 sq. units
  4. 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

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

Asked in: AP EAMCET 2019 (21 Apr Shift 2)

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