Answer to Question #47390 in Physics for tinu

Question

to cross a river across to the lowest distance,why the river has to run the boat creating an angle with the stream.as the question says that the boat has to cross it across the lowest distance which is the width of the river.so why not the angle between the boat and stream is not 90 degree?and here if it creates another angle then why not the total distance is more than the width?