1. **State the problem:** Find the length of the curve given by the vector function $$\mathbf{r}(t) = (\sqrt{2}t, e^t, e^{-t})$$ for $$0 \leq t \leq 1$$.
2. **Formula for curve length:** The length $$L$$ of a curve defined by $$\mathbf{r}(t)$$ from $$t=a$$ to $$t=b$$ is given by:
$$
L = \int_a^b \|\mathbf{r}'(t)\| \, dt
$$
where $$\mathbf{r}'(t)$$ is the derivative of $$\mathbf{r}(t)$$ and $$\|\mathbf{r}'(t)\|$$ is its magnitude.
3. **Find the derivative:**
$$
\mathbf{r}'(t) = \left( \frac{d}{dt}(\sqrt{2}t), \frac{d}{dt}(e^t), \frac{d}{dt}(e^{-t}) \right) = (\sqrt{2}, e^t, -e^{-t})
$$
4. **Find the magnitude:**
$$
\|\mathbf{r}'(t)\| = \sqrt{(\sqrt{2})^2 + (e^t)^2 + (-e^{-t})^2} = \sqrt{2 + e^{2t} + e^{-2t}}
$$
5. **Simplify the expression inside the square root:**
Recall that $$e^{2t} + e^{-2t} = 2\cosh(2t)$$, so:
$$
\|\mathbf{r}'(t)\| = \sqrt{2 + 2\cosh(2t)} = \sqrt{2(1 + \cosh(2t))}
$$
6. **Use the identity:**
$$1 + \cosh(2t) = 2\cosh^2(t)$$, so:
$$
\|\mathbf{r}'(t)\| = \sqrt{2 \cdot 2 \cosh^2(t)} = \sqrt{4 \cosh^2(t)} = 2\cosh(t)
$$
7. **Set up the integral for length:**
$$
L = \int_0^1 2\cosh(t) \, dt
$$
8. **Integrate:**
$$
\int 2\cosh(t) \, dt = 2\sinh(t) + C
$$
9. **Evaluate definite integral:**
$$
L = 2\sinh(1) - 2\sinh(0) = 2\sinh(1) - 0 = 2\sinh(1)
$$
10. **Final answer:**
$$
\boxed{L = 2\sinh(1)}
$$
This is the length of the curve from $$t=0$$ to $$t=1$$.
Curve Length 82C77E
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.