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暑假,老师给我们在QQ群中安排了“好题探究,惊喜连连”解题活动,大家参与积极性很高,收获颇丰.其中一题,经过老师的指导,在我们的合作下,给出了五种解法,现展示出来,与大家分享.题目(2007年四川文科卷第12题)如图1,l_1、l_2、l_3是同一平面内的三条平行直线,l_1与l_2间的距离是1,l_2与l_3间的距离是2,正三角形ABC的三顶点分别在l_1、l_2、l_3上,则△ABC的边长是
Summer vacation, the teacher gave us arranged in the QQ group, “a good topic to explore, surprise again and again ” problem-solving activities, we participate in a very high enthusiasm, very productive .One of the questions, after the teacher’s guidance, with our cooperation, Given five solutions, are now displayed, to share with you.The subject (2007 Sichuan Arts Volume 12) as shown in Figure 1, l_1, l_2, l_3 is the same plane in the three parallel lines, l_1 and l_2 distance Is 1, the distance between l_2 and l_3 is 2, the three vertices of the regular triangle ABC are respectively on l_1, l_2, l_3, then the length of △ ABC is