# Definition:Polar Coordinates/Polar Axis

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## Definition

Polar coordinates are a technique for unique identification of points on the plane.

Let $O$ be the pole of the polar coordinate plane.

A ray is drawn from $O$, usually to the right, and referred to as the polar axis.

## Also known as

Some sources refer to this as the initial line

Some use the term initial vector.

## Linguistic Note

The plural of axis is axes, which is pronounced ax-eez not ax-iz.

Compare basis.