An engineer designs a satelite dish with a parabolic cross section. The dish is 18 ft wide at the opening, and the focus is placed 9 ft from the vertex. a) Position a coordinate system with the origin at the vertex and the x-axis on the parabola's axis of symmetry and find an equation of the parabola. b) Find the depth of the satelite dish at the vertex. 4-92-Foo a) The equation for the parabola is (Type an equation. Simplify your answer.) (The figure may not be drawn to sca