Adish tv satellite dish is the shape of a paraboloid. the dish is 36 inches wide, and 8 inches deep. how many inches should the receiver be located from the vertex for optimal reception? (round to the nearest thousandth)

Refer to the diagram shown below. It shows a vertical cross-section of the paraboloid through its axis of symmetry.

Let the vertex of the parabola be at the origin. Then its equation is of the form
y = bx²

Because the parabola passes through (18,8), therefore
8 = b(18²)
b = 0.02469
The parabola is y = 0.02469x².

The receiver should be placed at the focal point of the paraboloid for optimal reception.
The y-coordinate of the focus is
a = 1/(4b) = 1/0.098765 = 10.125 in

The receiver is located at 10.125 inches from the vertex.