Question

The equation for the cross section of a parabolic satellite television dish is y = 1/45 x2, measured in inches. How far is the focus from the vertex of the cross section?

The distance from the vertex to the focus is _____ inches.

Answer 1

11.25

Explanation:

The equation for a parabola is:

y − k = 1/(4p) (x − h)²

where (h, k) is the vertex and p is the distance from the focus to the vertex.

1/(4p) = 1/45

4p = 45

p = 11.25

The distance from the vertex to the focus is 11.25 inches.