The obvious route, up a foot, along the ceiling and down eleven, is 42 feet. Unfold the room so the path crosses five of the six faces, the end wall, the ceiling, a side wall, the floor and the other end wall, and it becomes a straight line of exactly 40.
A room is 30 feet long, 12 feet wide and 12 feet high. A spider sits in the middle of one end wall, a foot below the ceiling. A fly sits in the middle of the opposite end wall, a foot above the floor, too frightened to move. What is the shortest distance the spider can crawl to reach the fly?
Give me a hintThe hint
Unfold the room flat, like a cardboard box, and draw a straight line.