Definition:Polar Coordinates

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

A distinct point $O$ is identified.

Identification of Point in Plane with Ordered Pair
Let $P$ be any point different from $O$.

Let a straight line $OP$ be drawn from $O$ to $P$.

Angular Coordinate

 * PolarCoordinates.png

The ordered pair $\left({r, \theta}\right)$ is referred to as the polar coordinates of $P$.

In order to distinguish them from those in Cartesian coordinates, points in polar coordinates are often found denoted within angle brackets: $\left\langle{r, \theta}\right\rangle$.

Historical Note
Polar coordinates were invented by in 1691.