A 4-ft-tall fence runs parallel to a wall of a house at a distance of 30ft. Assume the vertical wall of the house and the horizontal ground have infinite extent.

Let L be the length of theladder, x be the distance from the base of the ladder to thefence, d be the distance from the fence to the house and h be the distance from the ground to the point the ladder touches the house. What is the objectivefunction, in terms ofx?

Find the length of the shortest ladder that extends from theground, over thefence, to the house.