Final answer:
Boat A should adjust its trajectory based on vector addition principles, considering both boats' velocities and the water current to avoid a collision with boat B.
Step-by-step explanation:
When boat A is going head-on with an angle to boat B and needs to avoid a collision, boat A should adjust its steering to alter its trajectory and avoid crossing paths with boat B.
Since boat A has a certain velocity relative to the water and boat B has its own velocity, boat A must consider these factors to avoid a collision.
Boat A's captain should utilize the principles of vector addition to calculate the necessary angle and speed to maintain a safe distance from boat B.
This would involve considering the velocity of both boats and the current, then directing boat A's movement in a way that its resultant velocity avoids boat B.