- #1
RJLiberator
Gold Member
- 1,095
- 63
Homework Statement
Find the arc length of:
r(t)=<e^t, e^(-t),sqrt(2)*t>
from 0 to ln(2)
Homework Equations
L=integral from a to b of the magnitude of r'(t)
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.