def asymptote(self, x='x', y='y', equation=False, _slope=None):
        x0 = self.center.x
        y0 = self.center.y
        a = self.hradius
        b = self.vradius
        c = self.focus_distance
        x = self.directrix()[0]

        if _slope:
            k1 = (b + a * tan(_slope)) / (a - b * tan(_slope))
            k2 = (-b + a * tan(_slope)) / (a + b * tan(_slope))
            eq1 = y0 - k1 * (x - x0)
            eq2 = y0 + k2 * (x - x0)
        else:
            eq1 = y0 + (b / a) * (x - x0)
            eq2 = y0 - (b / a) * (x - x0)

        if equation:
            x = Symbol('x')
            y = Symbol('x')
            return Eq(y, eq1), Eq(y, eq2)
        else:
            return eq1, eq2

    def directrix(self, _x='x', _y='y', equation=False, _slope=None):
        x0 = self.center.x
        y0 = self.center.y
        a = self.hradius
        c = self.focus_distance

        if _slope:
            x = self.directrix()[0]
            eq1 = y0 - cot(_slope) * (x - x0) + (a ** 2 / c) * sqrt(1 + cot(_slope))
            eq2 = y0 - cot(_slope) * (x - x0) - (a ** 2 / c) * sqrt(1 + cot(_slope))
        else:
            eq1 = x0 + a ** 2 / c
            eq2 = x0 - a ** 2 / c

        if equation:
            x = Symbol('x')
            y = Symbol('x')
            return (Eq(y, eq1), Eq(y, eq2)) if _slope else (Eq(x, eq1), Eq(x, eq2))
        else:
            return eq1, eq2