If he crosses the river in minimum time \[x=\frac{du}{v}\] doneclear
B)
x can not be less than \[\frac{du}{v}\] doneclear
C)
For x to be minimum he has to swim in a direction making an angle of \[\frac{\pi }{2}+{{\sin }^{-1}}\left( \frac{v}{u} \right)\] with the direction of the flow of water doneclear
D)
x will be max. if he swims in a direction making an angle of \[\frac{\pi }{2}+{{\sin }^{-1}}\frac{v}{u}\] with direction of the flow of water doneclear