The Receiver in a Parabolic Satellite Dish Is 4 $a = 4.5$

Multiple Choice

The receiver in a parabolic satellite dish is 4.5 feet from the vertex and is located at the focus (see figure) .Write an equation for a cross section of the reflector.(Assume that the dish is directed upward and the vertex is at the origin. ) ​ $a = 4.5$ ​

A) $x = \frac { 1 } { 18 } y ^ { 2 } \text { or } y ^ { 2 } = 18 x$
B) $x ^ { 2 } = \frac { 1 } { 18 } y \text { or } y = 18 x ^ { 2 }$
C) $x = \frac { 1 } { 18 } y ^ { 2 } \text { or } y ^ { 2 } = 4.5 x$
D) $x ^ { 2 } = 18 y \text { or } y = \frac { 1 } { 18 } x ^ { 2 }$
E) $x ^ { 2 } = 4.5 y \text { or } y = \frac { 1 } { 18 } x ^ { 2 }$