弧长和扇形面积.doc

红旗教育个性化教案学生姓名： 年级： 科目： 英语 授课日期： 月 日上课时间： 时 分 - 时 分 合计： 小时教学目标了解圆锥母线的概念，理解圆锥侧面积计算公式，理解圆锥全面积的计算方法，并会应用公式解决问题 通过设置情景和复习扇形面积的计算方法探索圆锥侧面积和全面积的计算公式以及应用它解决现实生活中的一些实际问题重难点导航1重点：圆锥侧面积和全面积的计算公式2难点：探索两个公式的由来3关键：你通过剪母线变成面的过程教学简案： 一、 个性化作业二、 个性化教案三、 真题演练授课教师评价： 准时上课：无迟到和早退现象（今日学生课堂表 今天所学知识点全部掌握：教师任意抽查一知识点，学生能完全掌握现符合共 项） 上课态度认真：上课期间认真听讲，无任何不配合老师的情况（大写） 红旗作业完成达标：全部按时按量完成所布置的作业，无少做漏做现象 审核人：学生签字：教师签字：备注：请交至行政前台处登记、存档保留，隔日无效 （可另附教案内页） 大写：壹 贰 叁 肆 签章：一、复习引入 1什么是n°的圆心角所对的弧长和扇形面积的计算公式，并请讲讲它们的异同点2问题1：一种太空囊的示意图如图所示，太空囊的外表面须作特别处理，以承受重返地球大气层时与空气摩擦后产生的高热，那么该太空囊要接受防高热处理的面积应由几部分组成的 二、探索新知 我们学过圆柱的侧面积是沿着它的母线展开成长方形，同理道理，我们也把连接圆锥顶点和底面圆上任意一点的线段叫做圆锥的母线 问题2：与圆柱的侧面积求法一样，沿母锥一条母线将圆锥侧面剪开并展平，容易得到，圆锥的侧面展开图是一个扇形，设圆锥的母线长为L，底面圆的半径为r，如图24-115所示，那么这个扇形的半径为_，扇形的弧长为_，因此圆锥的侧面积为_，圆锥的全面积为_ 例1圣诞节将近，某家商店正在制作圣诞节的圆锥形纸帽，已知纸帽的底面周长为58cm，高为20cm，要制作20顶这样的纸帽至少要用多少平方厘米的纸？（结果精确到0.1cm2） 分析：要计算制作20顶这样的纸帽至少要用多少平方厘米的纸，只要计算纸帽的侧面积解： 例2已知扇形的圆心角为120°，面积为300cm2 （1）求扇形的弧长； （2）若将此扇形卷成一个圆锥，则这个圆锥的轴截面面积为多少？ 分析：（1）由S扇形=求出R，再代入L=求得（2）若将此扇形卷成一个圆锥，扇形的弧长就是圆锥底面圆的周长，就可求圆的半径，其截面是一个以底是直径，圆锥母线为腰的等腰三角形解：红旗教育个性化作业红旗教育错题汇编红旗教育个性化教案红旗教育真题演练一、用所给 adj.词的适当形式填空1. Hes as _( clever) his sister , but he doesnt do his homework as _( careful) as his sister. So he isnt so _( good) at his lesson as his sister.2. This coat is as _( nice) as that one but isnt so _( expensive) as that one.3. This kind of bike looks as _ as that kind but doesnt sell as _ as that kind(good)4. Tom runs as _( quick) as Kate, but he doesnt jump as_ as Kate.(high)5. He works as _as I. ,but his lessons arent as _ as mine.(hard, good)6. I have as _(many) money as you .7. Who picked _ apples, Jim , Mike or Lucy?(much)8. It was _yesterday than it is today.( hot)9. Apples are_ than pears.( delicious)10. Li Qings mother gets _( angry) because Li Qings school report is _( bad) than any other student in her class.11. It was quite _, I wont find anything _ than that. (cheap)12. She didnt feel _, so she went to the hospital yesterday, but now he feels _ .(well)13. He began to study _(hard) than last term, and he did _(well) than before, too.14. His _(old) brother is two years_(old) than him.15. No other boy in my class wrote so_(good) as Wei Lin.16. He always been _( careful) in his work but this time he works _( careless)17. Look _ (careful) at the drawing and you will understand what I mean.二、句型转换1. Meimei does her homework the most carefully of all the students in our class,Meimei does her homework _ _ than _ _ _ in our classMeimei does her homework_ _ than _ _ _ in our class.Meimei does her homework_ _ than _ _ in our class.Meimei does her homework_ _ than _ _ in our class.2. John is Cleverer than his brother.Johns brother _ _ _ _ John.3. Alices bike is more expensive than Li Qings bike.Li Qings bike _ _ _ _ Alices bike.4. The high jump is more difficult than the long jump.The long jump _ _ _ _the high jump.5. Whats your favorite sport?What sport _you like_?6. David didnt run as fast as Li LeiLi Lei ran _than David.7. Which coat do you like better? Which coat _you_?8. I like red better than black. I _red to black.9. I like singing better than dancing. I prefer_ to_. I prefer to _ rather than_.三、选择1. Mr. Smiths thought the Century Park was the second _ in Shanghai.A. large B. larger C. largest D. very large2. Which is _ of the two words?A. difficultB. the most difficultC. most difficult D. the more difficult 3. Is the physics problem_?Yes, I can work it out_.A. easy, easily B. easy, easy C. easily, easy D. easily, easily4. You look very _ .Have you got any good news?A. beautiful B. happy C. well D. tired5. I cant keep my eyes _. Im so sleepy.A. opening B. open C. closed D. closing6. Your bike is newer than _.A. my B. mine C. me D. I7. My brother is the youngest _ my family.A. than B. of C. for D. in 8. Its raining _.A. more and more hard B. harder and harder C. more hard and more hard 9. Spring is _ season _ the year.A. best in B. the best in C. bestof D. the bestof10. Betty is the most beautiful _.A. all her sistersB. of all the sisters C. of all her sisters D. in all her sisters11. His sister is two years_ than her.A. old B. older C. elder D. oldest12. Its _ to go there earlier.A. much good B. betterC. best D. the best13. Who jumped _ of all in the long jump?Ann did.A. longest B. longer C. farther D. farthest14. I dont think science is _ foreign languages.A. as more interesting as B. as interesting as C. as interesting than 15. India is the second_ population in the world?A. most B. largest C. more D. longest16. Our country is becoming _.A. more beautiful and beautifulB. more and more beautiful C. more beautiful and more beautiful四、选择最佳的答案完成下文。Dear Dr . Bamford I know you are a famous scientist who has done great work on cloning (克隆) animals . Please excuse me for writing to you, but I need your 1 . Let me explain .I am a 58-year-old man. Im very rich . I live in a large house . My wife died three years ago , we didnt have children . So, am I 2 ? No , because Cindy is with me . Every night we eat dinner together and watch TV . Cindy sits beside me 3 I feel very happy . Im fascinated (着迷的) with beautiful green eyes . Shes also very smart . Sometimes she thinks only about herself. But thats what I 4 about her . She is quite a beautiful Siamese cat .There is no other cat like her in the whole world .These days I worry about 5 Cindy . She is getting older and older . Cats dont live 6 humans, of course , so she will die before I do . I cannot imagine my life 7 Cindy .Well , why not get another cat after Cindy dies ? 8 ! No other cat ever replace (替代) her .I have been thinking about this : Clone Cindy . Scientists are able to clone sheep and mice and other animals. They should be able to clone cats without much 9 . Luckily , I am a rich man . I dont care how much money I will spend cloning Cindy . I think 10 to clone pets . Its not cloning humans.What do you think ? Could you clone Cindy ? Sincerely, A rich man ( )1. A. catB. animalsC. help ( )2. A. luckyB. lonelyC. happy( )3. A. butB. andC. or( )4. A. likeB. hateC. mind( )5. A. feedingB. catchingC. losing( )6. A. as hard asB. so often asC. so long as ( )7. A. withB. withoutC. about( )8. A. CertainlyB. ImpossibleC. Really( )9. A. difficultyB. adviceC. hope ( )10. A. its terribleB. you arent allowedC. its五、用恰当的词或句子完成对话。A: Its you , Jimmy ! When did you come to China ?B: Just this morning . At about 9 oclock .A: 1 ?B: By plane . It took me more than 30 hours .A: 2 ?B: It was pleasant . But I think it was so long .A: 3 ?B: Yes , a little . But Im feeling better after a nap(小睡) .A: Where are you staying now ?B: At the Grand Hotel . Its in the center of the city .A: Oh, its a good hotel .Then 4 .B: Thank you . I will .A: And Ill 5 .B: OK . Please call me before you come . Ill wait for you then .