Graphical axes, scales and coordinates

Graphical axes, scales and coordinates

To plot a graph, you know that we take two lines at right angles to each other (Figure 4.6). These lines being the axes of reference and they are known as Cartesian coordinates or rectangular coordinates where their intersection at the point zero is called the origin. When plotting a graph a suitable scale must be chosen, this scale need not be the same for both axes. In order to plot points on a graph we need to identify them by their coordinates. The coordinate points (2, 4) and (5, 3) are shown in Figure 4.6b. Note that the x-ordinate or independent variable is always quoted first. Also remember that when we use the expression plot s against t. Then all the values of the dependent variable s are plotted up the vertical axis and the other independent variable (in this case t) are plotted along the horizontal axis.