3. Two ports, A and B, on a North-South line are separated by a river of with D. The river flows east with speed Vw. A boat cross the river from port A to port B. The speed of the boat relative to the water is VB. Assume VB = 2Vw. State all your answers in terms of VB and D. (a) What is the direction of the boat, 0, relative to the North so that it crosses directly on a line from A to B? How long does the trip take? (b) Suppose the boat wants to cross the river from A to the other side in the shortest possible time. What direction should it head? (Hint: Think carefully about what this means.) How long does the trip take? How far is the boat from the port B after crossing?