说明：  1、一幢楼房的后面是一个很大的花园，在花园中紧靠着楼房有一个温室，温室为长方形，伸入花园，宽2米，高3米。温室正上方是楼房的窗台。清洁工打扫窗台周围时，得用***越过温室，一头放在花园中，一头靠在楼房的墙壁上。因为温室是不能承受***压力的，所以***太短是不行的。现清洁工只有一架长7米的***，你认为它能达到要求吗？能满足要求的***的最小长度是多少？
(1, a building behind a large garden in the garden close to the building have a greenhouse, the greenhouse is rectangular, stretching from the garden, 2 meters wide and three meters high. Greenhouse above the sill of the building. Cleaners cleaning the window sill around, starting a ladder across the greenhouse, a garden, one leaning against the walls of the building. Because the greenhouse is not to the ladder under pressure, so the ladder is too short is not enough. Cleaners are now only a long ladder of seven meters, and you think it will meet the requirements? To meet the requirements of the minimum length of the ladder is how much?)