# Parabola

A parabola is a curve that looks like the one shown above. Its open end can point up, down, left or right.
A curve of this shape is called 'parabolic', meaning 'like a parabola'.

There are three common ways to define a parabola:

## 1. Focus and Directrix

In this definition we start with a line (directrix) and a point (focus) and plot the
locus
of all points
equidistant from each.
For more see
Parabola (focus and directrix).

## 2. The graph of a function

When we plot the graph of a function of the form
the *x*^{2} term causes it to be in the shape of a parabola.
For more on this see
Parabola (Graph of a function).

## 3. As a conic section

A parabola is formed at the intersection of a plane and a cone when the plane is parallel to one side of the cone.

See Parabola (Conic section).

## Other quadratic equation topics

Quadratic Function Explorer

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