Noah wants to swim across a river 10 m wide, flowing from north to south. He swims so his velocity with respect to the river is 2 m/s due east, and the river moves at 4 m/s. How far downstream in m from his starting point will he reach the other side?

Answer 1

tan A = Y/x = -4/2 = -2.0
A = -63.43o = 63.43o South of East.

tan(-63.43) = d/10m
d = 10*tan(-63.43) = -20 m = 20 m. South
of starting point.