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《义务教育数学课程标准(2011年版)》明确要求:“学生能从较复杂的图形中分解出基本的图形,并能分析其中的基本元素及其关系,利用直观图形来进行思考.”笔者认为引导学生理解数学问题的本质,掌握一些基本图形,对学生学会从复杂图形中分解出基本图形,并灵活运用基本图形解决有关问题,提高几何解题能力有较大帮助.如图1,梯形ABCD中,AB∥DC,对角线AC、BD交于点O,根据同底等高,可得S△ACD=S△BCD,同时减去△DOC的面积,
“Compulsory Education Mathematics Curriculum Standard (2011 Edition)” clearly requires: “students can break down the basic graphics from the more complex graphics, and can analyze the basic elements and their relationship, the use of intuitive graphics to think. ” The author believes that guiding students to understand the nature of mathematical problems, master some basic graphics, students learn to decompose the basic graphics from complex graphics, and flexible use of basic graphics to solve the problem, improve the ability to solve geometric problems a great help.As shown in Figure 1, Trapezoidal ABCD, AB∥DC, diagonal AC, BD at the point O, according to the same height, available S △ ACD = S △ BCD, while subtracting △ DOC area,