The chord below is from Bach' violin sonata 3, Fuga
Up until this point the chords have been easy enough to at least figure out the fingering. In this case the fingering seems to be impossible.
Ive been trying 1, 4, 2, and arching 1 over awkwardly to hit the F.
1, 4, 3, 2 but that doesn't seem to work either. Spreading so far between 3 and 4 seems impossible.
2, 4, 3, 1 seems to make sense but is similarly awkward.
how is this typically done? Should I just ignore the A at the bottom?
For me it's "1, 4, 2, and arching 1 over awkwardly to hit the F.", executed more or less in the manner of an oblique barré, namely with 1 touching all the strings. As the A and D strings are separately fingered, it doesn't matter just what the index finger does with them: the only contact points that have to be precise and firm are with the G and E string.
I assume that you're playing this piece on violin, not on another instrument like mandolin. You're saved by the fact that the violin typically rolls across chords. See this long answer for an examination of the practice; note that the baroque-violin performer does the most roll of all. Even instruments that don't have to (harpsichord, lute) might be likely to roll this chord (it's important in its context, the first four-note chord after a bunch of three-note ones, and its wide span makes it so enjoyable). So you have time to use your first finger on G string, then whisk it away to E string as you roll across the middle two strings. This is really about the only workable option; attempting "barre" technique on violin, using one finger to stop all four strings, is near impossible to get a firm stoppage on all strings. And I'd encourage you, before you attempt heroic contortions of the left hand, to relax your understanding of "chord" and explore baroque practice: You're not an organ, and you're not obliged to sound all four pitches simultaneously or sustain them for the full duration.
