要求在该图中添一条线段，满足图中三角形的个数为15个。
计算：= ；﹣= ．
直接写出结果．1.2﹣0.8= 7.8+0.6= 5.44﹣3.6= 1﹣0.04=5.8+3.02= 0.67﹣0.58= ﹣= +=﹣=
直接写出得数．= = == = == = == = =
计算下面各题．．
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