Learn how to graph a horizontal parabola. A parabola is the shape of the graph of a quadratic equation. A parabola is said to be horizontal if it opens to the left or opens to the right. A horizontal parabola results from a quadratic equation in which the y part of the equation is squared. To sketch the graph of a parabola, we first identify the vertex, the focus and the directrix. To do this, we first write the equation in the form (y - k)^2 = 4p(x - h), where (h, k) is the vertex and p is the distance between the vertex and the focus. After expressing the equation in the form (y - k)^2 = 4p(x - h), the vertex is given by (h, k), the focus is given by (h + p, k) and the directrix is given by the line x = h - p. After obtaining the vertex, the focus and the directrix, we can then sketch the parabola.

Graphing a sideways parabola using the focus and directrix