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1、名师精编优秀教案课题6.5 三角形内角和定理的证明课 型新授课 时1 课时教材与学情分析学生在以前已经学习过平行线的判定定理与平行线的性质定理以及它们的严格证明，也熟悉三角形内角和定理的内容，而本节课是建立在学生掌握了平行线的性质及严格的证明等知识的基础上展开的，因此，学生具有良好的基础。教学目标（一）教学知识点三角形的内角和定理的证明.（二）能力训练要求掌握三角形内角和定理，并初步学会利用辅助线证题，同时培养学生观察、猜想和论证能力.（三）情感与价值观要求通过新颖、有趣的实际问题，来激发学生的求知欲.教学重点三角形内角和定理的证明.教学难点三角形内角和定理的证明方法.教学方法实验、讨论法.板
2、书设计6.5 三角形内角和定理的证明一、三角形内角和定理三角形三个内角的和等于180已知，如图ABC.求证：A+B+C=180备课时间：09 年 6 月 15 日审查签字：年月日A B C 名师精编优秀教案教学过程教学环节教师活动学生活动.巧设现实情境，引入新课探索新知回忆以前探索三角形内角和定理的过程？用折纸的方法验证三角形内角和定理实验 1：先将纸片三角形一角折向其对边，使顶点落在对边上，折线与对边平行（图（1）然后把另外两角相向对折，使其顶点与已折角的顶点相嵌合（图（2）、（3），最后得图（4）所示的结果。实验 2：将纸片三角形三顶角剪下，随意将它们拼凑在一起。三角形内角和定理：三角形三
3、个内角的和等于180已知：如图 2，ABC.求证：A+B+C=180 法一:图 2学生思考学生按照老师的要求动手操作（1）（2）（3）（4）图 1 学生尝试用自己的语言说明这一结论的证明思路。想一想，还有其它折法吗？用严谨的证明来论证三角形内角和定理 看哪个同学想的方法最多？文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF
4、10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 Z
5、F10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5
6、ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5
7、 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M
8、5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5
9、M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M
10、5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1名师精编优秀教案教学过程教学环节教师活动学生活动证明：作 BC 的延长线 CD，过点 C作射线 CEAB.则ACE=A（两直线平行，内错角相等）ECD=B（两直线平行，同位角相等）ACB+ACE+ECD=180（1 平角=180）A+B+ACB=180（等量代换）即：A+B+C=180.法三：图 4证明：如图 4，在 BC 上任取一点D，过点 D 分别作 DEAB 交 AC 于 E，DFAC
11、交 AB 于 F.四边形 AFDE 是平行四边形（平行四边形的定义）BDF=C（两直线平行，同位角相等）EDC=B（两直线平行，同位角相等）EDF=A（平行四边形的对角相等）BDF+EDF+EDC=180（1平角=180）A+B+C=180（等量代换）法二：图 3 证明：如图 3，过点 A 作直线 PQBC.PAB=B（两直线平行，内错角相等）QAC=C（两直线平行，内错角相等）PAB+BAC+QAC=180（1 平角=180）B+BAC+C=180（等量代换）法四：图 5 作 CA 的延长线AD，过点 A 作DAE=C，如图 5。学生可练习书写证明过程。文档编码:CY2V10W2G5N5 H
12、V5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5
13、HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5
14、 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N
15、5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5
16、N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G
17、5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2
18、G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1名师精编优秀教案教学过程教学环节教师活动学生活动反馈练习课时小结课后作业课本 P239随堂练习1、2.读一读
19、P240,你能想到什么？这堂课，我们证明了一个很有用的三角形内角和定理.证明的基本思想是：运用辅助线将原三角形中处于不同位置的三个内角集中在一起，拼成一个平角.辅助线是联系命题的条件和结论的桥梁，今后我们还要学习它.课本 P241习题 6.6 1、2、3 学生练习，老师巡视纠错，可找同学上黑板演练。学生思考。教后反思文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W
20、2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10
21、W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V1
22、0W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V
23、10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2
24、V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY
25、2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:C
26、Y2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1名师精编优秀教案文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U
27、2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6
28、U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S
29、6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9
30、S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T
31、9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10
32、T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1文档编码:CY2V10W2G5N5 HV5P10P6M5M5 ZF10T9S6U2J1