no, the directrix is 1.25 from the vertex! (not from the origin)
therefore the directrix is at -8 -1.25
and the focus is at -8 + 1.25
the equation of the parabola is (y-5)^2=5(x+8). Now I asked this earlier but that thread is farther down so no one sees it. He said the directrix is -9.25 but I think it is -1.25. Am I right?
4 answers
It would be a good idea for you to draw this parabola. it looks like a round bottom cup on its side with the opening to the right. The middle of the bottom of the cup is at the vertex. The focus is to the right of the vertex. The directrix is a vertical line to the left of the focus.
By the way, all points on the parabola are equal distances from the directrix on the left of the vertex (measured horizontal, perpendicular to directrix line), and from the focus to the right of the vertex.
oh! Ok thank you. I already do have it graphed as that is required. Thank you for all the help.