Construct a pentagon

This is where mathemagic gets tricky! This is not the only way to construct a pentagon, but I think it is pretty elegant.

I colorcoded the steps - do purple, then blue, then red. I've marked the centers of arcs with x's, and only drawn the arcs instead of the whole circle where I didn't need the whole thing.

This method uses pairs of arcs with equal radii to bisect angles and draw lines at right angles.

Enjoy!

For a cool animation of this, check out the wikipedia page:

http://en.wikipedia.org/wiki/Pentagon#Construction

Awesome Poster

This poster is beautiful:
http://informationesthetics.org/documents/scienceMapPrintMockupEd2.jpg

It maps the citation relationships between 800,000 scientific papers. Different disciplines are color-coded, so you can find your favorite. At full size, you can even find many sub-specialties labeled.

Full explanation here:
http://informationesthetics.org/node/20

I only wish that they had included some economics papers and the like ... I'd like to see the all-inclusive thought map!