A canoeist points their boat directly across a river perpendicular to the riverbank. They paddle at a speed of 4 km/h. The current pushes them downstream at 2.5 km/h.

1. a. What is the resultant velocity of the canoe? Include a vector diagram in your solution
2. b. The canoeist is trying to get to a dock directly across the river from their starting point. If the river is 800m wide, how far will they be from their destination when they arrive on the opposite bank of the river?