Polar coordinates (r, q) represent the location of a point (in 2D space) by its distance (r) from a fixed point on a fixed line (polar axis) and the angle (q, in radians) from that fixed line.

Polar plots are used to visualize functions. They also offer an intuitive way to present relations involving a variable representing direction.

See the Graph Layouts pane of the Graph Options dialog box; see also, Cartesian Coordinates.