As usual, there are a couple ways to go to get sin. But hopefully, you don't want calculator precision for your ..um .... calculator.

Melanie has a brilliant way. Old post, but I only recently discovered it.
http://www.picbasic.co.uk/forum/show...=2873#post2873

And doing it this way would also give you the ability to do sin, cos and atan2 on your calculator.
http://www.picbasic.co.uk/forum/showthread.php?t=10528