The Compendium Geometry is an eBook providing facts, formulas and explanations about geometry. 
Home Coordinate Systems 2D Cartesian Coordinate System  
See also: Polar Coordinate System, Conversion of Coordinates, Threedimensional Cartesian Coordinate System  
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Twodimensional Cartesian Coordinate SystemThe twodimensional Cartesian coordinate is defined by two axes, at right angles to each other, forming a plane (the xyplane). The horizontal axis is labeled x (sometimes called abscissa), and the vertical axis is labeled y (sometimes called ordinate). The point of intersection, where the axes meet, is called the origin, which is normally labeled O. To specify a particular point on a two dimensional coordinate system, you indicate the x unit first (abscissa), followed by the y unit (ordinate) in the form [x,y]. The two intersecting axes create four quadrants which are numerated counterclockwise by Roman literals. For example, the point P_{1} in the figure below lies in the first quadrant, the point P_{2} is located in the third quadrant.
The distance between a point P and the origin O calculates from the Pythagorean theorem: The distance between two points P1 and P2 calculates the same way as:


Home Coordinate Systems 2D Cartesian Coordinate System 