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

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) $\frac { \pi } { 4 }$