A boat that can travel at 4.60 km/h in still water crosses a river with a current of 1.80 km/h. At what angle must the boat be pointed upstream to travel straight across the river

The angle the boat must be pointed upstream is 69⁰

Explanation:

Check the image uploaded for the diagram;

Given;

speed of the boat on still water, = 4.6 km/h

speed of the boat on a river with current, = 1.8 km/h

The angle the boat must be pointed upstream is calculated as follows

b would be the answer

f=ma newton's second law 7x8=56n