“蚂蚁怎样走最近”这类问题,可借助长方体(或圆柱体)的侧面展开图,通过运用勾股定理、两点之间线段最短等数学知识来加以解决．例1(2005年·南充)如图1,长方体的高为3 cm,底面是正方形且边长为2 cm．现有一只蚂蚁从A点出发,沿长方体表面到达C点,蚂蚁行走的最短路线的长是( )． The problem of how ants can walk recently can be solved by the use of the cuboid (or cylinder) side expansion diagram and by using the Pythagorean theorem and the shortest line segment between the two points. Example 1 (2005 Nanchong) As shown in Figure 1, the cuboid height is 3 cm, the bottom surface is a square and the side length is 2 cm. An existing ant departs from point A and arrives at point C along the surface of the cuboid. The shortest path length the ant walks is ().