If the length is that (I didn't check it) then you should find it's minimum with respect to theta as they are asking for the shortest ladder.
A fence 2 feet tall runs parallel to a tall building at a distance of 6 feet from the building. What is the length of the shortest ladder that will reach from the ground over the fence to the wall of the building?
I am unsure what to do. my teacher helped me and said the length is 2 csc theta + 6 sec theta but i do not know where to go with this. please help thanks