二面角平面角的定义教学课件

1、二面角二面角1 、二面角及二面角的平面角的有关定义平面的一条直线把平面分为两部分，其中的每一部分都叫做一个半平面。从一条直线出发的两个半平面所组成的图形叫做二面角。（1）半平面（2）二面角llll这条直线叫做二面角的棱，每个半平面叫做二面角的面。1 、二面角及二面角的平面角的有关定义平面的一条直线把平BOAa（4）二面角的记法“面1棱面2” 如：以直线a为棱，以、为半平面的二面角记作：以直线AB为棱，平面CAB、平面DAB为半平面的二面角记作：等等。以直线l为棱，以平面ABCD、平面A1B1C1D1为半平面的二面角记作：或“AlA1”，等等。？“a”？“面ABCDl面A1B1C1D1”？“CA

2、BD”(3)常见二面角的画法BOAa（4）二面角的记法“面1棱面2” 如：以直B。OA(5)二面角的平面角垂直于二面角的棱的任一平面与两个半平面的交线所成的角叫做二面角的平面角。或： 从二面角的棱上任一点在两个半平面内分别作垂直于棱的射线，则这两条射线所成的角叫做二面角的平面角。B。OAB1。O1A1B。OA小结：B。OA复习回顾等角定理 若一个角的两边与另一个角的两边分别平行且方向相同，则这两个角相等。 1.二面角就是用它的平面角来度量的。一个二面角的平面角多大，我们就说个二面角是多少度的二面角。 2.二面角的平面角与点（或垂直平面）的位置无任何关系，只与二面角的张角大小有关。B。OA(5)

3、二面角的平面角垂直于二面角的棱的任一平(6)二面角的范围0。,180。（7）直二面角平面角为直角的二面角叫做直二面角(6)二面角的范围0。,180。（7）直二面角平面角为直当堂小测1、二面角指的是（）A、从一条直线出发的两个半平面所夹的角度。B、从一条直线出发的两个半平面所组成的图形。C、两个平面相交时，两个平面所夹的锐角。D、过棱上一点和棱垂直的二射线所成的角。2、二面角的平面角的顶点在二面角的上，角的两边分别在二面角的内，且两边都与棱，它的度数与它的平面角的度数。2.课堂诊断当堂小测1、二面角指的是（）2、二面角的平面角例1 在60。的二面角的棱上有两个点A、B，AC、BD分 别在二面角的

4、两个面内且垂直于AB，已知AB=4cm， AC=6cm，BD=8cm，求CD的长。 CDAB分析3.有关二面角的题型例1 在60。的二面角的棱上有两个点A、B，AC、BD分CD二面角平面角的定义PPT教学课件二面角平面角的定义PPT教学课件二面角平面角的定义PPT教学课件二面角平面角的定义PPT教学课件例3、如图，设E、F、G是正方体相应棱的中点，求二面角EFGA的大小。H解：如图，过点A作AH交CF的延长线于点H，连结EH。由EA平面AC及三垂线定理可得：EH FG，故EHA就是二面角 EFGA的平面角。例3、如图，设E、F、G是正方体相应棱的中点，求二面角EF本节小结小结1、二面角的定义2

5、、二面角的平面角的定义3、二面角的平面角的求解：找（或作）出平面角定义法棱的垂面法三垂线定理法向量法等求解解三角形或用向量的夹角公式本节小结小结1、二面角的定义3、二面角的平面角的求解：作业布置课本第47页4、5（3）作业作业布置课本第47页作业初一英语第二学期同步串讲 第七讲 Do you have an eraser?初一英语第二学期同步串讲 Do you have a soccer ball?二面角平面角的定义PPT教学课件soccer basketballbadmintonbaseballball gamessoccer basketballbadmintonbasetennis (r

6、acket)volleyballgolfPing pong (ball) table tennis tennis (racket)volleyballgolfPDo you have an American football / rugby?Yes, I do. /No, I dont.Do you have an American footbaGolf clubDo you have a golf ball?Yes, I do. / No, I dont.Golf clubDo you have a golf baGroup workNames Do you have a?Balls you

7、 haveLucyYes, I do. basketballWhat balls do you have? I have .Group workNames Do you have a1. 你有一个排球吗？ 是的，我有。2. 你有表兄妹吗? 不, 我没有。3. 她有网球拍吗？ 是的，她有。7. 咱们去踢球吧。Do you have a volleyball? Yes, I do.Do you have any cousins? No,I dont.Does she have a tennis racket? Yes, she does.Lets play soccer.1. 你有一个排球吗？ 是

8、的，我有。Do you 4. 他有英英字典吗？ 不，他没有。他有一本英汉字典。5. 他们有笔记本吗？ 是的，他们有。6. 让我看一看。Does he have an English English dictionary? No,he doesnt. He has an English Chinese dictionary?Do they have any note books? Yes, they do.Lets have a look.4. 他有英英字典吗？ 不，他没有。他有一本英汉字典。DoeDoes he have a tennis racket?Yes, he does. /No, h

9、e doesnt.Does he have a tennis racket?YDoes she have a soccer ball?Yes, she does. / No, she doesnt.Does she have a soccer ball?YeDoes he have a basketball?Yes, he does.Does he have a basketball?Yes,Do they have a puck?Yes, they do. /No, they dont.ice hockeyDo they have a puck?ice hockeyA: I want to

10、play baseball. Do you have a baseball bat?B: No, I dont. A: Does your brother have one?B: Yes, he does. Lets go and find him. A: I want to play baseball. DoLets play volleyball.That sounds good.Lets play volleyball.Lets play barbell.BarbellThat sounds boring.Lets play barbell.BarbellThatLets play bo

11、wling.That sounds interesting.Lets play bowling.That soundsLets play baseball.That sounds difficult.Lets play baseball.Lets go skateboarding.That sounds fun. (exciting)Lets go skateboarding.Lets play Ping Pong.That sounds relaxing.let sb. do sth.Lets have a break.Lets go and play Ping-pong. Lets pla

12、y Ping Pong.let sb. dOur School Sports Center needs new members. Fill in the enrollment form if you want to join the clubs. First name _ Last name _Age _ Sex _Class _ Club _Reason _Whats your first name, please? How old are you? What class are you in? What club do you want to join? Why? (Because I l

13、ike)Our School Sports Center need写出反义词dislike_ interesting _ good_ well_ easy_ lost _day _ different _big _ first _on _ in front of _this _ these _bring _写出反义词Fill in the blanks1. A: Excuse me, _ you _ a baseball?B: No, I _.A: _ Jim _ one?B: Yes, he _. Lets go and find him.2. A: Hi, Sally. B: Hi, Ja

14、ne. A: Sally, _ _ my friend, Lucy. B: Hi, Lucy. _ to meet you. C: Nice to _ you, _.do havedontDoes havedoesthis isNice meet tooFill in the blanksdo A: Lets play volleyball.B: That _ interesting, but I _ have one.A: Well, _ you have a tennis bat?B: Yes, I _. Lets go and play tennis.A: Thats a good _.

15、soundsdontdodoideaA: Lets play volleyball.soundDoes B have an eraser?Is the shop open? What day is today? What can they do? No, she doesnt.No, it isnt. It is closed.Today is Friday.They go to the supermarket.Part 1Does B have an eraser?No, she What would B like? How much money does B have? Where is

16、her purse? What does she do? She only has two yuan.Her purse is at home.She borrows four yuan from C.Part 2Shed like a red pencil and a pencil-sharpener.What would B like? Part 2Shed Does Jim have a dictionary? Does Ann have a dictionary? Who has an English-Chinese dictionary?4. When can Li Lei give

17、 it back? Part 3No, he doesnt.Lucy has one. He can give it back next Monday.No, she doesnt. Does Jim have a dictionary? P close * closed The shop closes at 8 pm. Please close the door. The door is closed. The shop is closed. The shop is open. close * closed The sh borrow from I borrow a book from hi

18、m. May I borrow a pen from you? Dont borrow money from her. May I May I come in? May I borrow a pen from you? May I sit down? borrow from I borrow a give back (to sb.) Please give the money back tomorrow.2. I can give the book back to him next week.3. Can you give my dictionary back this afternoon?

19、give back (to sb.) PleThere is something wrong with There is something wrong with my TV / his pen / your computer.2. There is something wrong with him / her / you/the boy. Whats wrong with you? Whats wrong with your TV?There is something wrong with close * closed borrow from May I give back (to sb.)

20、 There is something wrong with close * closed borrYou are going to have a P.E class, think about some activities. Talk about them.Time _ Place _Sport _Reason _You are going to have a P.E clWritingWrite a passage about yourself and your friend. What sports do you play? What sports things do you have?

21、 What other things do you do? What about your friend? (parent)WritingWrite a passage about yKey points: Food Do you like bananas? Does he /she like bananas?Do you like bananas ?Key points: FoodDo you like bDo you like oranges?Yes, I do. No, I dont.Do you like oranges?Does he like apples?Yes, he does

22、. No, he doesnt.Does he like apples?Does she like peaches?Yes, she does. No, she doesnt.Does she like peaches?Do they like grapes?Yes, they do. No, they dont.Do they like grapes?I like hamburgers for breakfast.But I dont like eggs.I like hamburgersBut I dont lDo your parents like pizza?Yes, they do.

23、No, they dont. Do your parents like pizza?Does your father like beer?Yes, he does.No, he doesnt.Does your father like beer?Choose the right words.There are five _( tomatoes, tomato) on the table.The _(child, children) are in the room.She _( doesnt like, dont like) chicken for lunch.He _(likes,like)

24、hamburgers.Choose the right words.5. Do they_(likes, like) apples?6. Mike doesnt like_( bananas, banana).7. My mother doesnt have _(a lunch, lunch) at home.8. Does she _(like, likes) French fries?5. Do they_(likes, like) a用所给动词的适当形式填空。She _(not like) salad._you _(like) oranges?He _(eat) lots of healthy food every day.There _(be) some chicken on the plate.His mother_(like) ice cream.用所给动词的适当形式填空。6. _your father _(