show that alpha must be obtuse.
A person, intending to cross a river by the shortest path, starts at an angle alpha with the downstream. If the speed of the person be less than that of water current, show that alpha must be obtuse.
21
Sep
A person, intending to cross a river by the shortest path, starts at an angle alpha with the downstream. If the speed of the person be less than that of water current, show that alpha must be obtuse. A person intending to cross a river by the shortest path show that alpha must be obtuse. [...]