From a point on a bridge across a river, the angles of depression of the banks on opposite sides of the river are 30° and 45° respectively. If the bridge is at a height of 3 m from the banks, then width of the river is
1
\(\frac{3}{{\sqrt 3 + 1}}\) m
2
\(3\left( {\sqrt 3 + 1} \right)\)m
3
\(\frac{{\sqrt 2 + 1}}{{100}}\) m
4
\(\rm 2 {\sqrt 2 + 1} \ m\)