整体思想在代数学习中经常用到 ,在解决几何问题时 ,我们往往习惯于将问题“化整为零” ,但有时候则需要我们从整体入手才能解决问题 .下面举例说明 .一、求线段的长度例 1　如图 1,在高 2米 ,坡角 3 0°的楼梯表面铺地毯 ,地毯的长度至少需要米 .(安徽省 1999年中考试题 )分析 The overall idea is often used in algebra learning. When solving geometric problems, we are often accustomed to “smoothing” the problem, but sometimes we need to start from the whole to solve the problem. Here are some examples. Length Example 1 As shown in Fig. 1, the surface of the stairs with a height of 2 meters and a slope angle of 30 degrees is covered with carpets, and the length of the carpet needs at least meters. (Anhui Province, 1999 mid-term exam questions) Analysis