SOLUTION: Write the equation of a parabola with vertex (1, -9) and directrix y = -9 - 7. What is the focus of the equation? What is the axis of symmetry?

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Write the equation of a parabola with vertex (1, -9) and directrix y = -9 - 7. What is the focus of the equation? What is the axis of symmetry?       Log On


   

Question 794245: Write the equation of a parabola with vertex (1, -9) and directrix y = -9 - 7.
What is the focus of the equation?
What is the axis of symmetry?
Answer by lwsshak3(11628) About Me  (Show Source):
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Write the equation of a parabola with vertex (1, -9) and directrix y = -9 - 7.
What is the focus of the equation?
What is the axis of symmetry?
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I assume you meant the directrix to be y=-7
Parabola opens downward
Its basic form of equation:(x-h)^2=-4p(y-k)
For given parabola:
p=2 (distance from vertex to directrix on the axis of symmetry)
4p=8
equation:(x-1)^2=-8(y+9)
axis of symmetry: x=1
focus: (1,-11) (p-distance below vertex on the axis of symmetry)