The Unit Circle Approach

The University of Idaho provides an online resource.  These lectures are only viewable by those with DSL or cable modems.  Real Player, a free download, is required to see these videos.
The Unit Circle
Given an angle, find the corresponding points on the unit circle
Evaluating the Trig ratios at 0,90,180,270,360

Watch the lesson on MathTV.com. Click the play button in the lower left corner of the video lesson screen.  It requires Real Player, a free download.

Dr. Jacci White of St. Leo University recorded this video that also requires Real Player.

TheMathPage.com