Q8 / 53 · NTA Abhyas (JEE Main) 2020 · Mathematics · Ellipse

A tangent having slope -43 to the ellipse x218 + y232=1 intersects the major and minor axes at A and B. If O is the origin, then the area of ΔOAB is

  • A
    48 sq. units
  • B
    9 sq. units
  • Correct answer
    C
    24 sq. units
  • D
    16 sq. units

Solution

Any point on the ellipse x2322 + y2422=1 can be taken as 32cos⁡θ, 42sin⁡θ and the slope of the tangent as - b2xa2y

Hence, slope=- 3232cos⁡θ18 42sin⁡θ=- 43cot⁡θ…. 1

Given, the slope of the tangent =-43…. 2

From equations (1) and (2), we get, 

cot⁡θ=1⇒θ=π4

Hence, the equation of the tangent is x.1232 + y. 1242=1

(i.e.) x6 + y8=1 

Hence, A=6, 0, B=0, 8

Area of ΔOAB=12× 6 × 8=24 sq. units

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

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