A river ?ows at a speed vr = 5.85 km/hr with respect to the shoreline. A boat needs to go perpendicular to the shoreline to reach a pier on the river's other side. To do so, the boat heads upstream at an angle ? = 37? from the direction to the boat's pier. If the time taken for the boat to cross the river is 13.8 min, determine the width of the river.