7. Find the width of the river

A person in the helicopter flying at the height of 621 $m$ above the river observes two objects lying opposite to each other on either bank of a river. The angles of depression of the objects are 30$^{\circ}$ and 45$^{\circ}$. Then, the width of the river is 1696.5721694.5721695.5721697.572 $m$.

 

(Note: Substitute $\sqrt{3} = 1.732$ if necessary.)