SOLUTION: I need help finding the Focus of a Parobola. The Vertex is (4,2) and the directrix is y=-3. Also if you are given the Vertex and focus can you find the directix?

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: I need help finding the Focus of a Parobola. The Vertex is (4,2) and the directrix is y=-3. Also if you are given the Vertex and focus can you find the directix?       Log On


   

Question 134460This question is from textbook
: I need help finding the Focus of a Parobola. The Vertex is (4,2) and the directrix is y=-3. Also if you are given the Vertex and focus can you find the directix? This question is from textbook

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
I need help finding the Focus of a Parabola. The Vertex is (4,2) and the directrix is y=-3.
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Draw the picture.
Notice that the vertex is 5 units above the directrix.
The focus must be 5 units above the vertex, or at point (4,7)
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Also if you are given the Vertex and focus can you find the directix?
Yes, every point on the parabola is an equal distance from the focus
and the directrix; that includes the vertex.
So the vertex is half-way between the focus and the directrix.
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Cheers,
Stan H.