conic sections --find eq of parabola that satisfies the given conditions focus(0,-3);directrix y=3?

Asked by  | 7th Mar, 2008, 08:01: PM

Expert Answer:

Let P(x.y) be any point on the parabola having its focus at S(0, -3) and directrix as the line y-3=0. then

SP=PM, where PM is the length of perpendicular from P on the directrix.

this implies SP square = PM square

(x-0) square + (y+3) square=  (y-3) square

On simplifying, this implies the eqation of parabola is

x square = -12y

Answered by  | 18th Mar, 2008, 07:03: PM

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