Three swimmers can swim equally fast relative to the water. they have a race to see who can swim across a flowing river in the least time. swimmer a swims perpendicular to the current and lands on the opposite shore downstream, because the current has swept him in that direction. swimmer b swims upstream at angle to the current, so that when she reaches the other side, she is straight across from where she started. swimmer c swims downstream at an angle theta in an attempt to take advantage of the current. who crosses the river in the least time?