Originally posted by talzamirLooks like 2 triangles 10x5 with the board being the length of the hypotenuse times two, or the square root of 125 times two= 22 feet and change. That would be if the board was carried in two dimensional space. I think the third dimension of 7 feet high, btw, the 5 foot wide corridor had an unspecified height so going by the exact wording, you can't strictly use the height so would have to treat it as a two dimensional passage.
A straight wooden plank that doesn't bend at all is carried in a long that is 10 feet wide and seven feet high. At one point there is a T-crossing to a side passage five feet wide. How long can the plank be if it makes it through the crossing?