If the normal of the parabola y 2 = 4 x drawn at the end points of its latus rectum are tangents to the…

If the normal of the parabola y2=4x drawn at the end points of its latus rectum are tangents to the circle x-32+y+22=r2, then the value of r2 is

Solution

End points of latus rectum A(1, 2), B(1, 2)
Equation of normal at Adydx=1
y-2=-1x-1
x+y-3=0 ...(i)
r= Distance of line (i) from 3, -2
r=3-2-32=2
r2=2

Asked in: JEE Advanced 2015 (Paper 1)

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