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Find the equation of line which is norma...

Find the equation of line which is normal to the parabola `x^(2)=4y` and touches the parabola `y^(2)=12x`.

Text Solution

Verified by Experts

Normal to parabola `x^(2)=4y` having slope m is
`y=mx+2+(1)/(m^(2))` (1)
It is tangent to `y^(2)=12x`.
Now, tangent to above parabola having slope m is
`y=mx+(3)/(m)` (2)
Comparing (1) and (2), we get
`(1)/(m^(2))+2=(3)/(m)`
`rArr" "2m^(2)-3m+1=0`
`rArr" "(2m-1)(m-1)=0`
`rArr" "m=(1)/(2)orm=1`
Therefore, equations of lines are 2y=x+12 or y=x+3.
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Knowledge Check

  • The equation of the normal to the parabola y^(2) =4ax at the point (at^(2), 2at) is-

    A
    ` tx+y=2at+at^(3)`
    B
    ` x+ty=2at+at^(3)`
    C
    `tx-y=at +2at^(3)`
    D
    `x-ty=at+2at^(3)`
  • The equation of directrix of the parabola 3x^2=-4y is

    A
    3y-1=0
    B
    3x-1=0
    C
    3y+1=0
    D
    3x+1=0
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