Question 290057
The set of points that are equidistant from a line y = -p (called the directrix) and a point (0,p) called the focus is a parabola. The equation can be written as:

x^2 = 4py

In this case p is 3 so the equation of the parabola is:

x^2 = 4*3y
x^2 = 12y

Google "parabola" for more background.