'The directrix of the parabola.
Returns
directrix : Line
See Also
sympy.geometry.line.Line
Examples
>>> from sympy import Parabola, Point, Line
>>> l1 = Line(Point(5, 8), Point(7, 8))
>>> p1 = Parabola(Point(0, 0), l1)
>>> p1.directrix
Line2D(Point2D(5, 8), Point2D(7, 8))'

@property
def directrix(self):

    return self.args[1]
