Finding the minimum time for crossing a river

[Abhimessi10]

Homework Statement

Finding the minimum time for crossing a river[/B]


how is the minimum time crossed by distance between the banks/velocity of swimmer with respect to ground as mentioned in the video?

Homework Equations

The Attempt at a Solution

The minimum time is only possible when velocity of man with respect to ground is at angle to the current flow so that he moves perpendicular to the river flow

 

[Dale]

The first thing to do in a problem like this is to write down an equation for the time as a function of the angle. Can you do that?