Are you building a standard truss, scissors truss or a truss with storage? I wish I had used a scissors truss to gain more ceiling height for at least half or 2/3 of floor space and other 1/3 for loft storage. Everything is a tradeoff. I built my own trusses too, but paid a structural engineer friend in beers and a dinner to give me the snow loads and design. 2x8 Rafters, 2x6 bottom chords... 24" o.c. 9/12 pitch. I don't think you need to worry about snow loads in Georgia - unless that freak storm drops a few feet. In hindsight - I should have just hired a truss company to build and deliver them...a lot of work. (to be honest, consider 2x6 rafters and bottom chords)
You can try a chalk layout on your shop floor for a full scale to layout a model truss and check your angles after calculating them.
Trigonometry and Pythagoras are your friends (many know this and just need a refresher...as for me? I had to start all over and re-learn these math skills). If there is a local HS math teacher there, buy him or her some beers and a dinner - and sit there to do the calculations for angles and lengths. (don't forget to add the rafter tail length after you calculate the rafter length...and a little extra to snap a chalk line on the tails after the trusses are up to make a nice straight fascia line.)
There are Trig Apps too to download into your phone. You will know several variables: the 90 degree angle, length from the one half of building width, Height of the roof - that will give you two legs of the triangle and more than likely you can calculate the hypotenuse (rafter) , opposite and complementary angles.
You may calculate the angles in 100th's of an inch. If you can acquire a framing square in 100th's that will help. Bit not necessary - just convert inch fractions to decimal....but you know this anyhow.
