My example of using the tools in this sketch:
[url]http://www.geogebratube.org/student/m480225[/url]
to make a Harriss spiral. Read more at:
[url]http://www.theguardian.com/science/alexs-adventures-in-numberland/2015/jan/13/golden-ratio-beautiful-new-curve-harriss-spiral[/url]
