What is the equation in standard form of the parabola with a focus at (12,-5) and a directrix of y= -6?
Because the directrix is a horizontal line, then the vertex form is
The the focal distance, f, is half of the vertical distance from the focus to the directrix:
h is the same as the x coordinate of the focus
The vertex form of the equation is:
Expand the square:
Use the distributive property: