See attached file for full problem description.
Please refer attachment.
a. i)Velocity vector diagram
The rower is subjected to two velocities simultaneously - the velocity of the river and his own rowing velocity. The rower will actually move in the direction of the resultant of these two velocities. As the rower wants to cross the river directly to the opposite bank i.e. wants to travel perpendicular to the bank, rower's resultant velocity must be in that direction. To achieve this the rower's velocity should be suitably directed as shown in the vector diagram below :
VA = 3 m/s
The resultant velocity of a rower crossing a river's current is determined.