« Parallel and Perpendicular Lines 

Each point in the polar coordinate system can be described with the two polar coordinates, which are usually called r (the radial coordinate) and θ (the angular coordinate, polar angle, or azimuth angle, sometimes represented as φ or t). The r coordinate represents the radial distance from the pole, and the θ coordinate represents the anticlockwise (counterclockwise) angle from the 0.
For example, the polar coordinates (3, 6) would be plotted as a point 3 units from the pole on the 6 ray.
From polar to cartesian coordinates.
Example 1:
Convert (3, ) into polar coordinates
Solution:
From cartesian to polar coordinates.
Example 2:
Convert (1,1) into polar coordinates
Solution:
This is a circle of radius and center (a, b).