The parabola has a vertex 
and the directrix with the equation 
.
Write down the equation of a given parabola and find its intersection with the abscissa axis.
Write down the equation of that circle with centre at the vertex of a given parabola which cuts a chord of length 8 from the directrix of the given parabola.
Show that one of the foci of the hyperbola with the equation 
lies on the directrix of a given parabola.
.
lies on the directrix 
of the parabola.
