Let $\mathbf { r } ( t ) = \cos ( 2 t ) \mathbf { i } + \sin ( 2 t ) \mathbf { j } + t \mathbf { k }$

Multiple Choice

Let $\mathbf { r } ( t ) = \cos ( 2 t ) \mathbf { i } + \sin ( 2 t ) \mathbf { j } + t \mathbf { k }$ Then the curvature K(t) is

A) 0
B) 1
C) $\frac { 4 } { 5 }$
D) 2
E) $\frac { 4 } { 13 }$