Look at the figure below. You have three house and there are three utilities below it: W representing water, G representing gas and E representing Electricity. You have to draw a line that gets each utility into every house without crossing the lines. Can you do it?
This puzzle is known as the Turan Brickyard Problem and is a classic one. There is no way that they can be connected without crossing the lines in 2 dimension. However, you can do it if you place the scene in a 3d workplace. See to the figure to understand better.
