A swimmer heads directly across a river, swimming at 1.5 m/s relative to the water. She arrives at a point 42 m downstream from the point directly across the river, which is 83 m wide.
(a) What is the speed of the river current?
(b) What is the swimmer's speed relative to the shore?
(c) In what direction should the swimmer head so as to arrive at the point directly opposite her starting point?