高一数学必须修读二2_3_3.ppt
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1、根据定义,一条直线与一个平面垂直,则这条直线和平面
内 。
任意一 条直线都垂直
2、在空间中,垂直于同一直线的两条直线互相平行。
3、垂直于同一平面的两直线互相平行。
1、在平面中,垂直于同一直线的两条直线互相平行。
4、垂直于同一条直线的两平面互相平行。
判断下列命题是否正确:
√
×
√
√
性质定理
2、根据判定定理,要判定直线与平面垂直,只需在
内找出 都与这条直线 。
平面
两条相交直线
垂直
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知识与技能
使学生掌握直线与平面垂直的性质:垂直于同一平面的两条直线平行,并会用性质定理解答问题。
过程与方法
培养学生的几何直观能力,使他们在直观感知,操作确认的基础上学会归纳、概括结论。
情感态度与价值观
培养学生学会从“感性认识”到“理性认识”过程中获取新知。
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(1)如图,长方体ABCD—A1B1C1D1中,棱AA1,BB1,
CC1,DD1所在直线都垂直于平面ABCD,它们之间具
有什么位置关系?
互相平行
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(2)如图,已知直线a,b和平面? ,如果a⊥?,b⊥?,那么,直线a,b一定平行吗?
证明:
O
反证法
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线面垂直的性质定理:
符号语言:
图形语言:
垂直于同一平面的两直线互相平行。
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根据直线与平面垂
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