They're essentially the same thing. But I tend to prefer TD's because it gets rid of all the messy radicals!
nyyfan0729: we're not here to do the problems for you step by step. (that's already done in your textbook and solution manual anyways) We're here to help you when you're stuck: you need to show us your thoughts on the problem, and what you've tried, so that we know where you're stuck and why.