ABC is an isosceles triangle right angled at A. Forces of magnitude $2 \sqrt 2,5$ and $6$ act along $\overrightarrow {BC},\overrightarrow{CA}$ and $\overrightarrow {AB}$ respectively. The magnitude of their resultant force is

Question

$\begin{array}{1 1} 4 \\ 5 \\11+2\sqrt2 \\30 \end{array}$