(© copyright 1996-1999, Timothy G. Feeman and Elaine F. Bosowski.)
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Cartesian Coordinate System; Polar Coordinate System; Rectangular Grid System;
The following sketch shows four points plotted in a typical Cartesian coordinate system.
Here is how the distance from a point to the origin is computed in Cartesian coordinates:
Horizontal and vertical lines have simple equations in Cartesian coordinates:
In polar coordinates, each point in the plane is located by its distance from the origin and the angle away from the reference direction (measured counter-clockwise).
Example: The set of points whose second coordinate is 30° forms a half-line emanating from the origin at an angle of 30° from the reference direction.
The sketch below shows a sample of a rectangular grid system. Suppose each square in the grid is 10 steps by 10 steps. If we start at the point labelled 1633, take 4 steps East and 5 steps South, then we will end up at the point labelled 164325.
