Answer:
Step-by-step explanation:
Given that a parabola has a vertex at the origin.
The equation of the directrix of the parabola is y = 3.
When directrix is a horizontal line y =3 we find that distance of vertex from directrix is 3 units.
By definition of parabola, the focus lies on the axis of parabola which here is x=0(since perpendicular to y=3 and through vertex)
Since any point is equidistant from focus and directrix,
we get vertex is 3 units down from origin on y axis.
Hence focus is (0,-3)
