We posed a problem of finding the length L of the shortest beam that can reach over a wall of height h to a tall building located k units from the wall. Use Lagrange multipliers to show that L = (h^2/3 + k^2/3)^3/2.

Data in Section 4.6, Exercise 39

The 8-ft wall shown here stands 27 ft from the building. Find the length of the shortest straight beam that will reach to the side of the building from the ground outside the wall.

Beam 8' wall -27'- Building