That does work, but he will still beast through it. My favorite way is to get on a high ledge above the troll and use the destruction spell firebolt or use a Flame Atronach to keep his health down. Once it is low, you can charge in with all your might with a good weapon and it will be a breeze. DO NOT try to simply stand in front of him and shoot flames unless you are at a safe distance. Even though they sort of limp towards you they are still kinda fast and if that troll gets to you he will rip you apart. I learned this the hard way going up the 7000 steps.