Straight line graphs
John Bird · 2012
A graph is a pictorial representation of information showing how one quantity varies with another related quantity. The most common method of showing a relationship between two sets of data is to use Cartesian or rectangular axes as shown in Figure 32.1. The points on a graph are called co-ordinates. Point A in Figure 32.1 has the co-ordinates (3, 2), i.e. 3 units in the x direction and 2 units in the y direction. Similarly, point B has co-ordinates (4, 3) and C has co-ordinates (3, 2). The origin has co-ordinates (0, 0). The horizontal distance of a point from the vertical axis is called the abscissa and the vertical distance from the horizontal axis is called the ordinate.