Coordinates and straight line graphs

Abstract

A straight line graph illustrates the relationship between two quantities. We have already looked at scatter diagrams in Section 9.5 which involve straight lines. In this chapter a variety of topics will be looked at which involve the use of straight lines. A very simple application is in the conversion from one quantity to another. Most people are aware that in measuring temperature, 0°C is the same as 32°F and 100°C is the same as 212°F. If these two relationships are plotted on a diagram similar to Figure 12.1, and the points are joined up with a straight line then we obtain a conversion graph between temperature in °C and temperature in °F. This graph can then be used to convert any temperature in °C to °F or °F to °C.