mathy question I think.

[Shadowknight]

This isn't for homework, it's for hanging christmas lights actually lol, but I can't figure it out and don't wanna screw it up. I'm trying to make a christmas tree kinda shape in my yard with some strings of light. it's a 16 foot string and I wanna hang them at a 30 degree angle. So my question is how long should the pole be? I know it has to be shorter than 16 degrees but I don't know the equation to figure out what length it should be.