I'm not too sure, since I don't know much about sine, but I'm pretty sure that the sine function is returning the wrong values in some cases. For instance, it claims that the sine of 180 is(roughly) 1.2, instead of the 0 it should be. But it gets really weird when I make a sine wave, where it creates a perfect sine wave with no visible problems. I've got a .CAP that will give you the sine for the angle you input for as well as a button that will create a sine wave:

Sine Calculator/Sine Wave

Am I just stupid, or is it actually giving out the wrong sine values?