What is the vertex form of the equation of the parabola with a focus at (-3,-9) and a directrix of #y=-10#?
1 Answer
Feb 11, 2016
Explanation:
The vertex of a parabola is always in between the focus and the directrix
From the given, the directrix is lower than the focus. Therefore the parabola opens upward.
p is 1/2 of the distance from the directrix to the focus
vertex #(h, k)=(-3, (-9+(-10))/2)=(-3, -19/2)
see the graph with directrix
graph{((x--3)^2-2(y--19/2))(y+10)=0[-25,25,-13,13]}
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