Something else you may do is a bit of cleaning of that partition.
Here is what i run for this to diagnose what is taking up space:
du -xak /|sort -n|tail -100
the last lines are the biggest folders or files.
You may well find that there is a redhat iso sitting in a directory you forgot about, etc ...
Also, you can move some data to another partition, and replace with a soft link.
Then if that's not enough, parted on a live CD is going to be your friend