Trig
posted by Stacey grahaM .
Suppose you would like to cross a 204 ft wide river in a boat. Assume that the boat can travel 37 mph relative to the water and the current is flowing westbat a rate of 6mph. What bearing should be chosen so that the boat will land at a point exactly across from the starting point?

Aim upstream at angle
A = sin^1(6/37) = 9.3 degrees
The upstream component of the boat's velocity relative to the water will then cancel out the river's flow speed.