Axis of Symmetry (Parabola)

Definition

The axis of symmetry of a parabola is a line about which the parabola is symmetrical.

When the parabola is vertical, the line of symmetry is vertical.

When a quadratic function is graphed in the coordinate plane, the resulting parabola and corresponding axis of symmetry are vertical.

Algebra

**STANDARD FORM**

The graph of the parabola represented by the quadratic function y = a( x - p )^{2} + q has an axis of symmetry represented by the equation of the vertical line x = p.

**GENERAL FORM**

Click here to see how this formula is derived.

**FACTORED FORM**