The sine of 30 radians is about -0.988 while the sine of 30 degrees is 0.5 .

The problem is that you work with radians instead of degrees I guess.

To change the angular setting, press "Mode" (this is a kind of menu, down-arrow to the 3rd line, highlight "Degree", press "Enter", then "2nd" and "Quit" to exit the mode screen.