0580

Coordinate Geometry

Coordinate Geometry and Graphs

Reading and plotting a point

  • The grid used throughout this course has a horizontal x-axis and a vertical y-axis, meeting at the origin
  • The origin is the point (0, 0), and every other point is described by how far it lies from there in each direction
  • A pair of coordinates is written in brackets with the horizontal value first: (x, y)
  • Positive x moves right and negative x moves left; positive y moves up and negative y moves down
    • (4, 3) sits four to the right and three up
    • (−2, −5) sits two to the left and five down
  • Plot a point with a small cross or a solid dot and label it, since an unlabelled mark cannot be credited
A squared grid with both axes running from −6 to 6 and a single labelled point A marked with a dot at three to the left and four up, the position written as (−3, 4)
Source: 2D coordinates by Save My Exams
  • Check the scale on the axes before counting: one square is frequently worth more than one unit, and assuming otherwise puts every answer out by a factor
  • The steepness of the line joining two points is dealt with separately, under linear graphs