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1、18.1 平行四边形课题18.1.1平行四边形的性质(1)课型新授三维目标知识目标理解并掌握平行四边形的概念和平行四边形对边、对角相等的性质。能力目标会用平行四边形的性质解决简单的平行四边形的计算问题,并会进行有关的论证。情感目标培养学生发现问题、解决问题的能力及逻辑推理能力。教学重点平行四边形的性质。教学难点运用平行四边形的性质进行有关的论证和计算。教学方法讲练结合教学过程创设情境,导入新课观察图形,引出平行四边形。明晰概念,证实发现你能总结出平行四边形的定义吗?(1)定义:两组对边分别平行的四边形是平行四边形(2)表示:平行四边形用符号“”来表示如图,在四边形 ABCD 中,AB DC,A
2、D BC,那么四边形 ABCD 是平行四边形平行四边形ABCD 记作“ABCD”,读作“平行四边形ABCD”平行四边形是一种特殊的四边形,它除具有四边形的性质和两组对边分别平行外,还有什么特殊的性质呢?我们一起来探究一下让学生根据平行四边形的定义画一个一个平行四边形,观察这个四边形,它除具有四边形的性质和两组对边分别平行外以,它的边和角之间有什么关系?度量一下,是不是和你猜想的一致?(1)由定义知道,平行四边形的对边平行根据平行线的性质可知,在平行四边形中,相邻的角互为补角(相邻的角指四边形中有一条公共边的两个角注意和第一章的邻角相区别教学时结合图形使学生分辨清楚)(2)猜想平行四边形的对边相
3、等、对角相等下面证明这个结论的正确性已知:如图ABCD,求证:ABCD,CBAD,BD,BADBCD分析:作ABCD的对角线 AC,它将平行四边形分成 ABC和CDA,证明这两个三角形全等即可得到结论(作对角线是解决四边形问题常用的辅助线,通过作对角线,可以把未知问题转化为已知的关于三角形的问题)证明:连接 AC,ABCD,ADBC,13,24又ACCA,ABCCDA(ASA)ABCD,CBAD,BD又 1423,BADBCD由此得到:平行四边形性质 1 平行四边形的对边相等文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5
4、R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4
5、文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5
6、R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4
7、文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5
8、R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4
9、文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5
10、R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4平行四边形性质 2 平行四边形的对角相等范例点击,演练提高教材 P42 例 1应用新知,练习巩固教材 43 页练习 1,2 题。概念延伸,拓展训练在以上学习的基础上,向学生讲解两条平行线之间的距离的概念。反思小结,观点提炼今天这节课你有什么收获?和小组内的同学交流一下。作业设置:习题 18.1 第 1,2,8,15 题。板书设计 18.1.1平行四边形的性质(1)一、平行四边形的概念二、平行四边形的性质例 1 课题18.1.1平行四边形的性质(2)课型新授三维目标知识目标掌握
11、平行四边形对角线互相平分的性质能力目标能综合运用平行四边形的性质解决平行四边形的有关计算问题,和简单的证明题情感目标培养学生的推理论证能力和逻辑思维能力教学重点平行四边形对角线互相平分的性质,以及性质的应用教学难点综合运用平行四边形的性质进行有关的论证和计算教学方法讲练结合文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编
12、码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y
13、1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编
14、码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y
15、1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编
16、码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y
17、1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4教学过程创设情境,导入新课复习提问:(1)什么样的四边形是平行四边形?四边形与平行四边
18、形的关系是:(2)平行四边形的性质:具有一般四边形的性质(内角和是360)角:平行四边形的对角相等,邻角互补边:平行四边形的对边相等探索研究,证实发现请学生在纸上画两个全等的ABCD和EFGH,并连接对角线 AC、BD 和 EG、HF,设它们分别交于点O把这两个平行四边形落在一起,在点 O处钉一个图钉,将ABCD绕点 O旋转180,观察它还和EFGH重合吗?你能从子中看出前面所得到的平行四边形的边、角关系吗?进一步,你还能发现平行四边形的什么性质吗?结论:(1)平行四边形是中心对称图形,两条对角线的交点是对称中心;(2)平行四边形的对角线互相平分平行四边形性质 3 平行四边形的对角线互相平分范
19、例点击,演练提高教材 P44 例 2应用新知,练习巩固教材 44 页练习 1,2 题。反思小结,观点提炼今天这节课你有什么收获?和小组内的同学交流一下。作业设置:习题 18.1 第 3,14 题。板书设计18.1.1 平行四边形的性质(2)平行四边形的性质3 平行四边形的对角线互相平分例 2文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2
20、D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8
21、H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2
22、D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8
23、H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2
24、D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4文档编码:CR4S8X3X8H6 HH5R3Y1R9I1 ZB4O2D2D2T4