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How to Graph a Vertical Parabola

How Graphs of Derivatives Differ from Graphs of Functions

How to Graph a Circle

To find the axis of symmetry start with the vertex. The vertex of this parabola is (3, 1). The axis of symmetry is at y = v, so for this example, it is at y = 1.
For the equation given, a = 1/8, and so the focal distance is 2. Add this value to h to find the focus: (3 + 2, 1) or (5, 1).
To find the directrix, subtract the focal distance from Step 2 from h to find the equation of the directrix. Because this is a horizontal parabola and the axis of symmetry is horizontal, the directrix will be vertical. The equation of the directrix is x = 3 – 2 or x = 1.
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