At what upstream angle must the swimmer aim, if she is to arrive at a point directly across the stream of a 42-m-wide river whose current is 0.50 m/s?

Question

At what upstream angle must the swimmer aim, if she is to arrive at a point directly across the stream of a 42-m-wide river whose current is 0.50 m/s?
A swimmer is capable of swimming 0.62m/s in still water.

Steve · Answer

Draw a diagram. If the swimmer swims upstream at an angle of θ, it is clear that sin θ = 0.50/0.65 Doesn't matter how wide the stream is, does it?