freeCodeCamp/guide/english/mathematics/axis-of-symmetry-of-a-parabola/index.md

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Axis of Symmetry of a Parabola

Axis of Symmetry of a Parabola

The axis of symmetry for a parabola is the line which perfectly bisects (or splits into two even parts) the parabola.

This is the same as a vertical line drawn at the x-value of the parabola’s vertex. Knowing this, you can find the line of symmetry easily by using the vertex form of a quadratic (parabolic) equation:

y = a(x-h)²+k

In this form, the coordinates of a parabola’s vertex is given by (h,k), meaning the equation of the line of symmetry will be x=h.