Aparabola has a vertex at the origin. the equation of the directrix of the parabola is y = 3. what are the coordinates of its focus? (0,3) (3,0) (0,–3) (–3,0)

Since the directrix is a horizontal line, the focus will be on the vertical line through the vertex and perpendicular to the directrix. The focus will be as far from the vertex as the directrix is, so will be 3 units from the origin in the downward direction.

The focus is (0, -3).

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Every point on the parabola is equidistant from the focus and the directrix, including the vertex point.