sorry to ask a theory question in the piano forum but i think pianists here are quite familiar with the piece.

i have to analyze the chord progression in measure 28 - 40 of the piece for homework. the problem is that there is a long low C pedal below the chords, so what would be more appropriate to do??
1. I ignore the C pedal or 2. I write something like G major chord 2nd inversation with a C in the bass???

Debussy was exploring alternatives to traditional tonality. You can't describe his work in terms of inversions of traditional major/minor chords.
Suggest you hit the uni. library and do a bit of reading.. that's what homework is for, no?!

You can't just ignore the C in the bass - if you do you'll get it wrong. The piece may be experimenting with atonality, but basically it's still in C. What you have to do is find out what chord in C can have a C in the bass and what appears to be (in the example you've chosen) a G major chord above it (etc.). The answer lies in not thinking in triads but in extended chords. For instance, C E G B would be Cmaj7 (C7 is C E G Bb) and C G B D might be described as C9 (though I'm sure alternative descriptions also work). I believe that a lot of Jazz musicians study Debussy for exactly this sort of reason. Of course it helps to have a working (even if rusty) knowledge of jazz scales and extended chord theory. Another "of course" I could be wrong!! Good luck.