A lot of curriculum are pretty messed now a days. But what Im thinking is that your school managed to take pre-calculus and throw in a bit of calculus in there as well.
strange, but I can't know for sure. Im in senior year (final year) and it is the first year we ever did anything related to calculus.
also one bad math test won't shake up your mark too bad, in my school the teachers will usually grade you on your most consistent performance so if you got 90's all year and got a 60 on a test they would probably drop it. Good luck on the rest of your stuff pusga!