Question 824838
This question is a classic piece of instruction.  The directrix is a line, and the focus is a point.  The worded definition for a parabola can be stated as, the set of points in a plane equally distant from the focus and the directrix.


You would use the Distance Formula to set up your crude form equation and then simplify into a convenient form.


DO YOU HAVE SOME SPECIFIC GIVEN DATA TO BEGIN?  Do you want a parabola with a horizontal axis or one with a vertical axis?