Boat A is located 4 km north and 2.5 km east of ship B. Ship A with a speed of 22 km/h is moving towards the south, and ship B with a speed of 40 km/h is moving at an angle of 37 degrees to the northeast (37 degrees measured from east to north). (a) What is the speed of ship A relative to ship B in unit vector notation (i for east), (b) when is the distance between the ships the smallest and what is the smallest distance?