| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| x1x2 |
| 1 |
| x2x3 |
| 1 |
| x3x4 |
| 1 |
| x1999x2000 |
| 1 |
| 1×2 |
| 1 |
| 2 |
| 1 |
| 2×3 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3×4 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4×5 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 2003×2004 |
| 1 |
| 2003 |
| 1 |
| 2004 |
| 1 |
| 2003 |
| 1 |
| 2004 |
| 1 |
| n(n+1) |
| 1 |
| n |
| 1 |
| n+1 |
| 1 |
| n(n+1) |
| 1 |
| n |
| 1 |
| n+1 |
| 1 |
| 1×3 |
| 1 |
| 3×5 |
| 1 |
| 5×7 |
| 1 |
| 2003×2005 |
(2012·常德)若图1中的线段长为1,将此线段三等分,并以中间的一段为边作等边三角形,然后去掉这一段,得到图2,再将图2中的每一段作类似变形,得到图3,按上述方法继续下去得到图4,则图4中的折线的总长度为( )