Math 101 Intermediate Algebra
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The Cartesian Coordinate System
Chapter 3, Section 1

Cartesian Coordinates--Overview

  • Locate points in 2-D by specifying where the point is relative to the Origin.
  • Any point may be specified by an ordered pair (described below).
  • The horizontal line labeled "x" is the x-axis.
  • The vertical line labeled "y" is the y-axis.
  • Quadrants are regions of the plane relative to the origin.
    Quadrant I: x > 0 and y > 0
    Quadrant II: x < 0 and y > 0
    Quadrant III: x < 0 and y < 0
    Quadrant IV: x > 0 and y < 0


Ordered Pairs (x, y)

  • Any point in 2-D may be located by an ordered pair (x, y).
  • The x-coordinate, x, is the value on the x-axis vertically above or below the point.
  • The y-coordinate, y, is the value on the y-axis horizontally right or left of the point.
  • The order is that the x-coordinate is listed first and the y-coordinate is listed second.


Distance Formula

The distance formula gives the distance, d, between 2 given points (x1, y1) and (x2, y2).

Distance is always non-negative.


Midpoint Formula

The midpoint formula gives an ordered pair that is the point halfway between 2 given points (x1, y1) and (x2, y2).