Here's a spreadsheet that may (or may not ) be useful:

Click on the picture to download the spreadsheet

You enter parametric equations for a few curves, type in some ranges for the independent variables, click a few buttons and ...

>Huh?
There's an Explain sheet which looks like this:

>And that's useful? It's fun! You can fiddle with the graphs, play with the colours, stick in a few interesting points ... Neat, eh? >zzzZZZ