The first thing that should be shown in any Trigonometry class, done in Canvas (humblesoftware.com)

You are getting sleepy... very very sleepy.

Seriously, I started feeling drowsy watching that.

Something similar:

http://en.wikipedia.org/wiki/File:Pi-unrolled-720.gif

I've always loved watching that relationship.

Once you've added cos & tan and you can go home early, trig's done!

Super, super awesome. Just a few niggles:

- The pi marker on the x axis stays fixed. As far as I can tell it doesn't really refer.

- phi is increasing, but the construction of the graph makes it look like phi should be decreasing. Seems like the circle should be on the right, with the line moving leftward and the phi values marked on the x axis receding in that direction as well.

- I'd like to be able to drag the graph around.

No one likes a whiner, so I tweaked a bit: http://doormouse.org/trig