document.write( "Question 1187810: Space Science. A designer of a 200-foot-diameter parabolic electromagnetic antenna for tracking space probes wants to place the focus 100 feet above the vertex (see the figure). Find the equation of the parabola using the axis of the parabola as the y axis (up positive) and vertex at the origin.
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Algebra.Com's Answer #819176 by Solver92311(821) $\"\"$ $\"About$

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Sunday, April 2, 2017
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\n" ); document.write( "\n" ); document.write( "The equation of a parabola with a vertical axis is

, where the vertex is at the point

and

is the directed distance from the vertex to the focus.\r
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\n" ); document.write( "\n" ); document.write( "In this case, since the focus is 100 feet above the vertex at

. Then, because the vertex is at

you have

and

, and you have all the information you need to write the equation simply by substituting values into the vertex form.\r
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\n" ); document.write( "\n" ); document.write( "Since the diameter of the antenna is 200 feet, i.e. 100 feet on each side of the vertex, you should specify the domain of your function to be

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\n" ); document.write( "John
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\n" ); document.write( "My calculator said it, I believe it, that settles it
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\n" ); document.write( "\n" ); document.write( "From
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