A parabola is the curve formed by the intersection of a plane and a cone, when the plane is at the same slant as the side of the cone.
A parabola is also defined as the set of all points in a plane which are an equal distance away from a given point (called the focus of the parabola) and a given line (called the directrix of the parabola).
In beginning algebra, we usually consider only parabolas whose axis of symmetry is vertical. The equations for these curves are in the general form
y = ax2 + bx + c,
where a, b and c are constants.
See also graphing quadratic equations.