Let the Position Function of a Particle Be $\mathbf { r } ( t ) = \langle 3 \sin 2 t , 2 \cos 2 t , - \sin 4 t \rangle$

Multiple Choice

Let the position function of a particle be $\mathbf { r } ( t ) = \langle 3 \sin 2 t , 2 \cos 2 t , - \sin 4 t \rangle$ . Find the speed of the particle when $t = \frac { \pi } { 4 }$ .

A) 1
B) 4
C) 3
D) $4 \sqrt { 2 }$
E) $\sqrt { 8 }$
F) $\sqrt { 10 }$
G) $\sqrt { 13 }$
H) $\sqrt { 14 }$