三角形的内角说课稿市名师优质课比赛一等奖市公开课获奖课件.pptx

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styles,Second level,Third level,Fourth level,Fifth level,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,第十一章 三角形,11.2.1,三角形内角（,2,）,第1页,【,学习目标,】,1,、掌握直角三角形表示方法，并了解直角三角形性质与判定；,2,、能利用直角三角形性质与判定处理实际问题。,【,学习重、难点,】,重点：了解和利用直角三角形性质与判定。,第2页,【,预习导学,】,一、自学指导,1,、自学,1,：自学书本,P13,14,页，掌握直角三角形表示方法及其性质，完成以下填空。,5,分钟,总结归纳,：直角三角形能够用符号,表示，直角三角形,ABC,能够写成,。,直角三角形两个锐角,。,三角形是直角三角形。,“,Rt,”,RtABC,互余,有两个角互余,第3页,【,预习导学,】,二、自学检测,：,学生自主完成，小组内展示、点评，教师巡视。,10,分钟,1,、在,RtABC,中，,C,90,，,A,2,B,，,求出,A,、,B,度数？,解：,RtABC,中，,A+B,90,（直角三角形两个锐角互余）,A,2,B,2B+B,90,B,30,，,A,60,第4页,【,预习导学,】,2,、如图，,ACB,90,，,CD,AB,，垂足为,D,，,AC,D,与,B,有什么关系？为何？,结论：,AC,D,B,理由以下：在,Rt,ACB,中，,A,+B,90,在,Rt,ACD,中，,A+,AC,D,90,AC,D,B,点拨精讲：,利用同角余角相等能够方便证出两角相等关系。,3,、如图，,C,90,，,AED,B,，,ADE,是直角三角形吗？,为何？,结论：,ADE,是直角三角形,理由以下：在,RtABC,中，,A,+B,90,（直角三角形两个锐角相等）,AED,B,A,+AED,90,ADE,是直角三角形（有两个角互余三角形是直角三角形）,第5页,【,合作探究,】,小组讨论交流解题思绪，小组活动后，小组代表展示活动结果。,10,分钟,证实：,AB/CD,BAC+ACD,180,AE,、,CE,分别平分,BAC,、,ACD,EAC=,EAC+,A,CE,ACE,是,Rt,（有两个角互余三角形是直角三角形）,ACD,BAC,，,A,CE,BAC+,ACD,90,探究,1,已知：如图，,AB/CD,，,AE,、,CE,分别平分,BAC,、,ACD,；求证：,ACE,是,Rt.,第6页,【,合作探究,】,小组讨论交流解题思绪，小组活动后，小组代表展示活动结果。,10,分钟,探究,2,如图，在,RtABC,中，,C,90,，,AD,、,BD,是,CAB,、,CBA,角平分线，求,D,度数。,解：在,RtABC,中,CAB+CBA=90,AD,、,BD,是,CAB,、,CBA,角平分线,DAB=,DAB+DBA,在,ADB,中，,D,180,（,DAB+DBA,）,180,45,135,CBA,CBA,C,A,B,，,DBA,C,A,B+,45,第7页,【,跟踪练习,】,学生独立确定解题思绪，小组内交流，上台展示并讲解思绪。,5,分钟,1,、在,ABC,中，,A,:B:C,1,：,2,：,3,，则此三角形是,；,2,、已知：如图，在,ABC,中，,ACB,90,，,AC,D,B,；,求证：,ACD,是,Rt.,证实：在,RtABC,中，,A,+B,90,（直角三角形两个锐角互余）,AC,D,B,A,+ACD,90,ACD,是,Rt,（有两个角互余三角形是直角三角形）,直角三角形,第8页,【,点拨精讲,】,（,3,分钟）,1,、直角三角形性质：两个锐角互余。,2,、直角三角形判定：,有一个角是直角；,两边相互垂直；,有两个角互余；,第9页,【,课堂小结,】,（学生总结本堂课收获与迷惑）,2,分钟,【,当堂训练,】,10,分钟,第10页,