# Definition:Polar Coordinates/Angular Coordinate

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## Definition

Let $P$ be a point in a system of polar coordinates where $O$ is the pole.

The angle measured anticlockwise from the polar axis to $OP$ is called the angular coordinate of $P$, and usually labelled $\theta$.

If the angle is measured clockwise from the polar axis to $OP$, its value is considered negative.

## Also known as

The angular coordinate is also known as the polar angle, or azimuth.

Some sources use the word amplitude.

Some sources use vectorial angle.

The word inclination is also seen.

Beware the term azimuth, as it is used in astronomy in a similar but significantly different way, to mean the angle measured clockwise from north.

Sometimes south is used.