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Question 624989: please help me solve this (What is the equation of a parabola with a vertex at (1, -1) and a directrix y = 4
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! please help me solve this (What is the equation of a parabola with a vertex at (1, -1) and a directrix y = 4
Form of equation for a parabola that opens downwards: (x-h)^2=-4p(y-k), (h,k)=(x,y) coordinates of the vertex.
For given parabola:
vertex: (1,-1)
axis of symmetry: x=1
p=5 (-1 to 4) (distance from vertex to directrix on the axis of symmetry)
4p=20
equation: (x-1)^2=-20(y+1)
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