Q29 / 40 · NTA Abhyas (JEE Main) 2020 · Mathematics · Hyperbola

Let the variable line y=kx+h is tangent to the hyperbola x24-y29=1. If the locus of Ph,k is a conic, then which of the following statement is false about this conic?

  • A
    Vertices of conic lies on y-axis
  • B
    The eccentricity of conic is greater than the eccentricity of given hyperbola.
  • C
    The centre of conic is at the origin
  • Correct answer
    D
    The conic is an ellipse

Solution

Equation of the tangent y=kx+h is compared with y=mx±4m2-9
⇒1=mk=±4m2-9h
i.e. m=k and h=4m2-9
⇒h=4k2-9
⇒4y2-x2=9
⇒y2322-x232=1
⇒32=322e2-1
⇒e2=5⇒e=5>1

Hence, the conic is not an ellipse

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

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