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>>>"...understanding that sin represents the y value of a point on a unit circle..."

Wow, I'm enrolled in a college trig class right now and your comment just made me realize that. Thanks for the heightened understanding :)

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For the sake of completeness, cos is the x value, because of the identity sin(x)^2 + cos(x)^2 = 1. You should find a good unit circle trigonometry picture if your class isn't giving it to you.

Wikipedia's picture is frightening (http://en.wikipedia.org/wiki/Unit_circle), but perhaps http://www.themathpage.com/atrig/unit-circle.htm or http://www.snow.edu/jonathanb/Courses/Math1060/unit_circ_tri... will help.

What I find especially ironic is that while I completely understood that I could get the x and y values using rcos(t) and rsin(t) and used it a lot when I worked for a video game company, it's only more recently that the idea "clicked". I always thought about sin and cos in relation to triangles and not circles.

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