a little experimentation
Never mind, I discovered the answer with a little impromptu LCDing.
What is unclear in the manual is that the angle in degrees is represented by a value of 0-255 instead of 0-359. It's NOT in radians as the manual suggests (where a decimal value of 6.28 radians would correspond to 360 degrees). To calculate the value to pass to the function SIN x, you have to use x=255y/360 where y was your angle in degrees.
The result returned from the SIN function is in the range of 0-255, in two's compliment form (where 0-127 corresponds to a scaled sin result of 0.00 to 1.00 respectively and 128-255 corresponds to a scaled sin result of -1.00 to 0.00 respectively).
Although it's not super accurate, it's reasonably adequate to 2 decimal places if you figure 0-127 scaling is better than 1 to 100.
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