1. The problem statement, all variables and given/known data r(t)=<t^2,lnt,tlnt> 2. Relevant equations k= |T '(t)| / |r '(t)| 3. The attempt at a solution My professor's answer sheet solved the problem using the other method, k(t)=|r '(t) x r ''(t)| / |r '(t)|^3 and that answer ends up being 0.3, while mine is 0.4. I can't see where I made any mistakes, and why I got 9 points marked off. Can someone explain?