Equation for Parabola with Given Focus and Width: Homework Problem

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SUMMARY

The discussion focuses on deriving the equation of a parabola for a parabolic communications antenna with a focus located 6 feet above its vertex. The standard form of the parabola is established as (x-h)^2 = 4p(y-k)^2, leading to the equation x = 24y^2 when the vertex is positioned at the origin (0,0). Additionally, the width of the antenna at a distance of 9 feet from the vertex is addressed, emphasizing the importance of correctly identifying the vertex and focus in the equation formulation.

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  • Knowledge of the focus and vertex of a parabola
  • Familiarity with coordinate geometry
  • Basic algebraic manipulation skills
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Homework Statement


A parabolic communications antenna has a focus 6 feet above its vertex. Write an equation for the parabola and find the width of the antenna 9 feet from the vertex. Locate the origin strategically.


Homework Equations



y= x^2 (parent equation for parabola)

The Attempt at a Solution


focus = 4p.
standard form of parabola , (x-h)^2 = 4p(y-k)^2
4 * 6 = 24 so (x-h)^2 = 24(y-k)^2.
It doesn't give you the origin how are you supposed to write the formula?
 
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(h,k) is the vertex. You can put the origin anywhere you like. Why not put it at the vertex? So (h,k)=(0,0). Now what's the y coordinate 9 feet from the vertex? BTW, check your standard form for a parabola. You've got an extra square in there.
 
Hello...

Dick said:
You've got an extra square in there.

I believe you're right. The equation is (x-h) = 4p(y-k)^2

or (y-k) = 4p(x-h)^2

So, just try x = 24y^2 and work from there ^^
 

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