The Radius of Curvature Of $\mathbf { r } ( t ) = 2 t \mathbf { i } + \left( t ^ { 2 } - 1 \right) \mathbf { j }$

Multiple Choice

The radius of curvature of $\mathbf { r } ( t ) = 2 t \mathbf { i } + \left( t ^ { 2 } - 1 \right) \mathbf { j }$ at the point corresponding to t = 1 is

A) $4 \sqrt { 2 }$
B) $\frac { 1 } { 2 \sqrt { 2 } }$
C) 2
D) $\frac { 101 \sqrt { 101 } } { 12 }$
E) $\frac { 7 } { 125 }$