1. The problem statement, all variables and given/known data Find the arc length of: r(t)=<e^t, e^(-t),sqrt(2)*t> from 0 to ln(2) 2. Relevant equations L=integral from a to b of the magnitude of r'(t) 3. The attempt at a solution Okay, this was an Exam question, the one exam question that I could not get on our Calc 3 exam. This breaks down into an integral. The answer is 3/2 and there seems to be an obvious trick that I am missing. r'(t)=<e^t, -e^(-t), sqrt(2)> Take the magnitude sqrt((e^t)^2+(-e^-t)^2+2) Take the integral of that from 0 to ln(2). There is some trick here that I simply could not get. I spent an hour on this problem during the exam :p.