Plotting a point on a graph.
In the early days of mathematics, geometry was primarily done with compasses and straight edges. The emergence of computer graphics, where pixels on the screen are identified by their positions on the X and Y axes, has made coordinate geometry much more practically important. With traditional compass-and-straight edge geometry, the orientation of a line would often be described by its angle to the vertical in degrees, but in coordinate geometry, it is often more conveniently described by its slope, or the Y coordinate's rate of change relative to the X coordinate.
Instructions
1. Mark the two points on your line A and B, and find their respective X and Y coordinates. For example, point A might be (1,5) and point B might be (7,3).
2. Subtract the X coordinate of point A from the X coordinate of point B. In the example, 7 - 1 = 6.
3. Subtract the Y coordinate of point A from the Y coordinate of point B. In the example, 3 - 5 = -2.
4. Divide the difference in Y coordinates by the difference in X coordinates. The result is the slope of the line. In the example, the slope is -1/6, which means that for every one unit you travel along the line in the X axis, you go down 1 sixth of a unit in the Y axis.
