I teach math. There are actually many moms on here that are math teachers or just very good at math. You could always try posting one of the problems here. You never know, we might be able to help.
You might be surprised at the number of times someone has posted a math problem from their child's homework and received some excellent responses with, not only the correct answer, but pretty good explanations.
ETA - I also agree with those who say tell the teacher. The teacher should know this!
Also, did you try asking your daughter to explain it to you? I had a horrible geometry teacher and basically had to teach myself. Every time I got stuck I asked my dad for help. He would ask me some questions and get me to explain things to him. Somewhere in my explanations I always answered my own question. Years later my dad admitted that he really had no idea what I was doing, but asking me questions got me to think about it and figure it out.
If your daughter gets stuck on a problem, have her tell you how she did the previous problems. It might help her figure out what she needs to do. If it doesn't work, at least she's had a chance to explain what she's done so far, and you can send a note letting the teacher know what she was and was not able to do.