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中考试题中,有许多题目难度并不大,但命题者有意设计“陷阱”,制造障碍,如果同学们的基础知识掌握不牢或粗心大意,便会误入这些“陷阱”,造成解题的失误．一、利用概念模糊设计“陷阱”例1 (2005年潍坊市)已知圆A和圆B相切,两圆的圆心距为8cm,圆A的半径为3cm,则圆B的半径是()．A.5cm B.11cm C.3cm D.5cm或11cm错解：由R+r=8,得圆B的半径为5cm．故选A．
In the middle-test questions, there are many questions that are not too difficult, but propositioners are interested in designing “traps” and creating obstacles. If the students’ basic knowledge is not solid or careless, they will stray into these “traps” and cause problems. Mistakes. First, use the concept of fuzzy design “trap” Example 1 (Weifang City, 2005) known circles A and B tangent, the two circles of the center-to-center distance of 8cm, the radius of the circle A is 3cm, then the radius of the circle B is () . A.5cm B.11cm C.3cm D.5cm or 11cm misinterpretation: from R + r = 8, to obtain a circle B radius of 5cm. So choose A.