Thank you all! I was just trying to figure out how I could simply measure with a bit of math on larger panels and be fairly accurate before making the cut.
I just use my 12" digital protractor, set to 22.5 degrees, to layout about a foot long line on the panel, then place my track saw track on the line and cut it.
That's my simplified math method.
The only time consuming part is taking the cover off and sticking the battery in the protractor, then taking the battery back out for storage.
Makita and Festool both make a protractor attachment for the track saws that just slips on the track that are mechanical and require no battery, but, as far as I can tell - neither has a 22.5 degree or 45 degree stop, so a protractor is still required for setup.
I don't wish to sidetrack the thread - but - so many people have the attitude that track saws are just for breaking down sheet goods, I like to point out how simple they can make other tasks.
"Life is what happens to you while you're busy making other plans." - John Lennon