parabola

the largest value of a for which the circle x2+y2 = a2 lies completely inside the parabola y2 = 4(x+4)

6 Answers

262
Aditya Bhutra ·

a= 2√3 ??

1
aditya ravichandran ·

set Discriminant=0

1
fahadnasir nasir ·

Deff cirle equation 2xdxdy+2y=0 → dxdy=-yx
Deff parabola eq 2y=4dxdy → dxdy=12y
that means -yx=12y
xy+2y=0
x+2=0 →x=-2
y2=8
y=2√2
from circle eq a=2√3

1
rishabh ·

i still dint get it... fahad dint understand your method.
does some1 have another method?

1
fahadnasir nasir ·

rishabh, the concept is that the the two curves of circle and parabola intersect when the slopes of the two curves are equal.

1
rishabh ·

alright,got it. thanks!

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