The Vector R(t) Is the Position Vector of a Particle $\mathbf{r}(\mathrm{t})=\mathrm{e}^{6 \mathrm{t}_{\mathrm{i}}+\left(4+\mathrm{e}^{-6 \mathrm{t}}\right) \mathrm{j}+(7 \cos 8 \mathrm{t}) \mathbf{k}}$

question 38

Multiple Choice

The vector r(t) is the position vector of a particle at time t. Find the angle between the velocity and the acceleration vectors at time t = 0.
- $\mathbf{r}(\mathrm{t}) =\mathrm{e}^{6 \mathrm{t}_{\mathrm{i}}+\left(4+\mathrm{e}^{-6 \mathrm{t}}\right) \mathrm{j}+(7 \cos 8 \mathrm{t}) \mathbf{k}}$

• A) 0
• B) \(\frac { \pi } { 3 }\)
• C) \(\frac { \pi } { 2 }\)
• D) \(\frac { \pi } { 4 }\)

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