shuxuejianmo_2

说明：  一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,温室伸入花园2m,高3m,温室正上方是楼房的窗台. 清洁工打扫窗台周围,他得用梯子越过温室,一头放在花园中,一头靠在楼房的墙上. 因为温室是不能承受梯子压力的,所以梯子太短是不行的. 现清洁工只有一架7m长的梯子, 你认为它能达到要求吗? 能满足要求的梯子的最小长度为多少?(The back of a building is a big garden. In the garden close to a building in a greenhouse, greenhouse into the garden 2m, high-3m, the greenhouse is the top of the building' s bay windows. Cleaners cleaning around the windowsill, he crossed to use a ladder greenhouse, on a garden, against a building wall. because of the greenhouse can not bear the pressure of a ladder, so the ladder is not too short. cleaners are only a 7m long ladder, do you think it can meet the requirement it? ladder to meet the requirements of the minimum length of the number?)