directrix
The parabola is a plane curve defined as the set of all points that are equidistant from a fixed point \(F \) called the focus, and a fixed line \( d \) called the directrix.
The parabola is a plane curve defined as the set of all points that are equidistant from a fixed point \(F \) called the focus, and a fixed line \( d \) called the directrix.