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1、首先是从三角形面积公式开始， S = 1 底高2于是出现两种等面积模型：（1）（2）BCmABDCBD:CD=1 : 1nA Dm n两个图中均有面积 SDABD = SDACD ，这是最基本的模型，由它延伸出来的有：（1）推论：ASDABD = aB DCBD:CD=a : bSDACDbADBCEBD:CD=a : bSDABE SDACE= a （也叫风筝模型）bFABDCBD:CD=a : bSDABF SDACF= a （也叫燕尾模型）注意此模型的应用！bAGHBCAG:AB=a : 1AH:AC=b : 1SDABH SDABC= b ， SDAGHSDABH= a ， 故 SDA
2、GHSDABC= ab （也叫共角模型）举例连结CE （题目中第一空所求应为阴影面积之和）由 BD = 2 知 S CDDABD= 2 S3DABC， SDACD= 1 S3DABCA又 AE = ED ，故 SDABE= SDDBE= 1 S3DABC ，SDCDE= SDACE= 1 S6DABC ，EF AF = SDABE FCSDBCE=SDABE= 2SDBDE + SDCDE3BDCSDAEF= AE AF = 1 ， 即 S = 1 SSDACDAD AC5DAEF15 DABC一半模型：DECA ABCD 中， SDABE= SDABD= 1 S2ABCDABEDCABFE
3、为梯形 ABCD 腰上中点， SDADE= 1 S2DADF= 1 S2ABCDGEDCA B共边定理（ （2）的重要推论 ）：AE 、G 为中点， S阴影= 1 S2 ABCDESDABD = ACSDBDECEB DC“”“”At the end, Xiao Bian gives you a passage. Minand once said, people who learn to learn are very happy people. In every wonderful life, learning is an eternal theme. As a professional cl
4、erical and teaching position, I understand the importance of continuous learning, life is diligent, nothing can be gained, only continuous learning can achieve better self. Only by constantly learning and mastering the latest relevant knowledge, can employees from all walks of life keep up with the pace of enterprise development and innovate to meet the needs of the market. This document is also edited by my studio professionals, there may be errors in the document, if there are errors, please correct, thank you!
