Question 1092181
<br>Assuming an upward opening parabola with its vertex at the origin, the vertex form of the equation of a parabola that I like to use is<br>
{{{y = (1/(4p))x^2}}}<br>
With that form of the equation, the parameter p is the distance from the vertex to the focus and the distance from the vertex to the directrix.<br>
We can use the given information to find the value of p and thus determine how far from the vertex the receiver should be.<br>
If we picture the parabola as opening upward with its vertex at the origin, then the outermost points on the dish are at the points (6,4.5) and (6,-4.5). So<br>
{{{4.5 = (1/(4p))(6^2)}}}
{{{9/2 = 9/p}}}
{{{p=2}}}<br>
So the receiver should be placed 2 feet from the vertex.