So anything up to 45 degrees is simple, either on a mitre/compound/chop saw, or on a table saw with a mitre gauge/crosscut sled. However, more than that is tricky.
Mitre saws are out, because they usually only go up to 45-50 degree angles, and would require the work material to be sticking out towards you. Similar problem on a table saw, though at least a sliding table or extension would help support the material.
What's the best way forward? Let's say I wanted to make an equilateral triangle, for example.