Q19 / 40 · NTA Abhyas (JEE Main) 2020 · Mathematics · Hyperbola

Two straight lines having variable slopes m1 and  m2 pass through the fixed points a,0 and -a,0 respectively. If m1m2=2, then the eccentricity of the locus of the point of intersection of the lines is

  • A
    2
  • Correct answer
    B
    3
  • C
    2
  • D
    32

Solution

Let, the lines are y=m1x-a and y=m2x+a

which intersects at the point h,k.

⇒k=m1h-a &  k=m2h+a

⇒k2=m1m2h2-a2

⇒k22=h2-a2 (given, m1m2=2)

⇒x21-y22=a2 (Hyperbola)

Eccentricity =1+21=3

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

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