计算
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101190823730141286/SYS201311011908237301412012_ST/0.png)
的结果是
.
考点分析:
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图1是一个边长为1的等边三角形和一个菱形的组合图形,菱形边长为等边三角形边长的一半,以此为基本单位,可以拼成一个形状相同但尺寸更大的图形(如图2),依此规律继续拼下去(如图3),…,则第n个图形的周长是( )
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D.
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