Two Towns
Below you see two graphs. the top one depicts a landscape - if you like, think of the positive x-axis as East and positive y-axis as North. There are two towns A and B in the landscape with coordinates (10,20) and (20,10)
It turns out that the significant information that we need to have at any point is our distance DA from A and our distance DB from B. For each point, that information gets plotted on a set of DA-DB axes. What we will need to be able to do is easily translate the information from one graph to the other.
