Problem 4.4
The shortest distance is represented by moving the point F over the dotted line. This was found by reflecting the tent over the river to where you would see its reflection in the water. So basically the camper needs to run towards the reflection then once reaching the river they need to turn and go towards the tent. I believe this has something to do with a straight line towards the reflection being the shortest path. Sort of how the shortest path across a street is straight across. Going directly at the reflection might not be the shortest path to the river, but it creates the shortest total distance travelled.