algebra helppp?

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does anyone know how to write the equation of a parabola if you're only given the focus and the directrix?

2007-01-15 16:33:43 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics

2 answers

See the instructions at http://home.alltel.net/okrebs/page64.html

If you need more help, give a holler

2007-01-15 16:39:16 · answer #1 · answered by teachbio 5 · 0⤊ 0⤋

suppose S(6,0) and l is the line x=0let (x1,y1) be a point on the parabola
SP=rt[(x1-6)^2+(y1-0)^2]
PM=perpendicular distance from P to the directrix
x=0=x1
fore parabola SP=PM
=>SP^2=PM^2
(x1-6)^2+y1^2=x1^2
-12x1+36+y1^2=0
locus is y^2-12x+36=0

2007-01-16 00:48:06 · answer #2 · answered by raj 7 · 0⤊ 0⤋