一、直线与平面平行
1.直线与平面平行的定义
文字叙述:直线file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png与平面file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png没有公共点,则称直线file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png与平面file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png平行.
符号语言:file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.pngfile:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image008.pngfile:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image010.png
2.直线与平面平行的性质定理
文字叙述:一条直线与一个平面平行,则过该直线的任一平面与此平面的交线与该直线平行
符号语言:若file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image012.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image014.png,则file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image016.png
3.直线与平面平行的判定定理
文字叙述:平面外一条直线与此平面内的一条直线平行,则该直线与该平面平行
符号语言:若file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image018.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image020.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image022.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image024.png,则file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image022.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png
教科书39页例1(线面平行的判定定理)
例3(1.空间中线面之间的关系的应用;2.将空间中的几何问题转化为平面内的几何问题)
活页70页第6题(1.学会根据题意画出示意图;2.线面平行的判定)
活页70页第9题(线面平行的判定)
活页70页第11题(线面平行的判定,一题多解)
二、平面与平面平行
1.平面与平面平行的定义
文字叙述:两个平面file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image028.png没有公共点,则称这两个平面平行
符号语言:file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image028.pngfile:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image008.pngfile:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image032.png
2.平面与平面平行的性质定理
文字叙述:两个平面平行,则任意一个平面与这两个平面相交所得的交线互相平行
符号语言:若file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image028.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image034.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image036.png,则file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image038.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image040.png
3.平面与平面平行的判定定理
文字叙述:一个平面内的两条相交直线与另一个平面平行,则这两个平面平行
符号语言:若file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image042.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image044.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image046.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image038.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image028.png,file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image040.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image028.png,则file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image004.png∥file:///C:/Users/ADMINI~1/AppData/Local/Temp/msohtmlclip1/01/clip_image028.png
教科书41页例4(面面平行可转化为线面平行)
活页71页第6题(线面平行的判定(通过面面平行实现线面平行))
活页71页11题(面面平行的判定(通过线面平行实现面面平行))
小结:
1.线线平行,线面平行,面面平行可以实现两两之间的相互转化
2.转化的思想是较为重要的数学思想,在立体几何中,转化的思想尤其重要且体现得特别明显,多加留意
3.通常情况下,转化的基本思路是尽量将空间问题转化到平面中来解决.即:立体问题平面化