What does the line y=k-1/4a represent in y=a(x-h)^2+k, the standard form of equation for a parabola?

The line y=k-1/4a represent in y=a(x-h)^2+k is:

                                   Directrix.              

Directrix of a parabola--

A directrix is a line which is perpendicular to the axis of symmetry of a parabola and it does not touch the parabola.

Also, for the standard equation of the parabola i.e.

The equation of directrix of a parabola is given by:

mental cunning

explanation:

he is often referred to as a man of twists and turns

one set of data has more variation than the other. hope this !