问题
问答题
In the figure above, two searchlights S1 and S2 are located 10,000 feet apart, each covers an area of radius 10,000 feet, and each is located 8,000 feet from the railroad track. To the nearest 1,000 feet, what is the total length x of track spanned by the searchlights ？
答案
参考答案：
6,000×2+10,000=22,000英尺
解析：
如上图所示由S1，S2向铁轨道做垂线，垂足分别为B和C，根据题意可知BC=S1S2=10,000英尺，S1B=S2C=8,000英尺，S1A=S2D=10,000。根据勾股定理得：
[*]
所以AD的长度为：
6,000×2+10,000=22,000英尺