教 学 过 程教师 行为学生 行为教学 意图时间 *揭示课题 8.4 圆(二) *创设情境 兴趣导入 【知识回顾】 我们知道,平面内直线与圆的位置关系有三种(如图8-21): (1)相离:无交点; (2)相切:仅有一个交点; (3)相交:有两个交点. 并且知道,直线与圆的位置关系,可以由圆心到直线的距离d与半径r的关系来判别(如图8-22): (1):直线与圆相离; (2):直线与圆相切; (3):直线与圆相交. 介绍 讲解 说明 质疑 引导 分析 了解 思考 思考 带领 学生 分析 启发 学生思考 0 15*动脑思考 探索新知 【新知识】 设圆的标准方程为 , 则圆心C(a,b)到直线的距离为 . 比较d与r的大小,就可以判断直线与圆的位置关系. 讲解 说明 引领 分析 思考 理解 带领 学生 分析 30*巩固知识 典型例题 【知识巩固】 例6 判断下列各直线与圆的位置关系: ⑴直线, 圆; ⑵直线,圆. 解 ⑴ 由方程知,圆C的半径,圆心为. 圆心C到直线的距离为 , 由于,故直线与圆相交. ⑵ 将方程化成圆的标准方程,得 . 因此,圆心为,半径.圆心C到直线的距离为 , 即由于,所以直线与圆相交. 【想一想】 你是否可以找到判断直线与圆的位置关系的其他方法? *例7 过点作圆的切线,试求切线方程. 分析 求切线方程的关键是求出切线的斜率.可以利用原点到切线的距离等于半径的条件来确定. 解 设所求切线的斜率为,则切线方程为 , 即 . 圆的标准方程为 , 所以圆心,半径. 图8-23 圆心到切线的距离为 , 由于圆心到切线的距离与半径相等,所以 , 解得 . 故所求切线方程(如图8-23)为 , 即 或. 说明 例题7中所使用的方法是待定系数法,在利用代数方法研究几何问题中有着广泛的应用. 【想一想】 能否利用“切线垂直于过切点的半径”的几何性质求出切线方程? 说明 强调 引领 讲解 说明 引领 讲解 说明 观察 思考 主动 求解 思考 主动 求解 通过例题进一步领会 注意 观察 学生 是否 理解 知识 点 50
一、实行走班管理的原则 1、为了组织师生安全、有序、高效地进行走班上课,我们将本着“从小处着眼,积极稳妥,有序推进”的原则,选课、走班原则上在同一年级内进行。 2、学生根据学校提供的选修课程,自主填报选修课程选择志愿,学校根据学生志愿并结合师资与场地条件,组建所开设课程的教学班。 3、选修课程教学班管理实行课程导师负责制。课程导师是教学班的核心,是选修课程教学班中教学、纪律、财物、安全管理的第一负责人。课程导师由教学班任课教师担任,任课教师担任几个班的选修课程教学,就相应担任几个班级的课程导师。 4、教学班实行走班小组制管理。选修课程导师应在课程第一讲前,以原行政班为单位,将学生划分为几个走班学习小组,固定学生座位,确定教学班教学座位表,每次教学中学生座位不允许随意调换。
全省ZT教育开展以来,省委第二、第四巡回指导组认真贯彻中央部署和省委要求,牢牢把握督促指导工作的正确方向,紧扣主题主线,把握重点关键,高标准、严要求,扎实推动联系指导单位ZT教育不断向纵深发展。省委第x巡回指导组——开展“融入式”指导推动ZT教育见行见效“在这里上课效果怎么样?”“结课后可以拿到资格证书吗?”“后续你们的就业问题工会能否帮助解决?”近日,省委第x巡回指导组来到xx市xx区xx超市(西湖区新就业形态联合工会)调研,指导组成员与来到劳务超市进行月嫂培训的学员交流,了解联系指导单位省总工会二级机构运行情况。这是省委第x巡回指导组统筹自身建设和指导工作,推动ZT教育走深走实的生动实践。全省ZT教育开展以来,省委第x巡回指导组按照中央决策部署和省委工作要求,统筹理论学习、调查研究、推动发展和检视整改,指导省委组织部等xx家单位扎实开展ZT教育,取得积极成效。
2004年的雅典奥运会上,孔令辉获得冠军时忘情地亲吻胸前的国徽时,王军霞夺得金牌后激动的身披国旗绕运动场奔跑时,我们的泪水也会与领奖台上以手抚着胸前国徽高唱国歌的运动员的热泪一起落下。为了看体育比赛,我们甚至不惜守候到半夜而无怨无悔。在半夜看比赛时,我总在想:是什么让我们“为伊消得人憔悴”,为什么“总有一种力量让人泪流满面”。现在我有了答案:那是一种奥林匹克精神在激励着我们,在提升着我们。奥林匹克精神的内涵是丰富的。国际奥委会主席罗格在其就任宣言中指出:“奥林匹克的格言是更快、更高、更强。在新世纪来临的时候,或许对体育来讲需要新的格言,那就是更干净、更人性、更团结。” 奥林匹克精神让我们振奋,今天我们就来学习这篇课文《庆祝奥林匹克运动复兴25周年》。
(3)推荐男女生代表各一位在全班进行演讲展示。 (4)围绕“讲”和“演”两方面的技巧,点评演讲效果。(生开展演讲活动,师指导)【设计意图】本环节通过集中梳理演讲技巧,并设计演讲技巧进行演讲展示,引导学生将理论知识逐步运用于具体的演讲实践中,提高学生的演讲能力。五、总结存储1.教师总结现代奥林匹克运动的创始人顾拜旦面对世界政治格局剧变的局面,以战略家的视野指出奥林匹克精神的内涵与价值,用诗歌般的语言阐述了奥林匹克平和自信的内涵,提出了奥林匹克运动的宗旨是教育,是面向大众,是促进和平、公平、公正。他激情澎湃地畅想美好前景,确信奥林匹克精神必将如阳光般普照大地。整篇演讲词站位高、格局广,语言庄重、典雅,值得我们用心体会。2.布置作业学校即将举行春季运动会,如果你被邀请在运动会的开幕式上作为学生代表发言,你将如何演讲?结合你对奥林匹克运动的精神的理解,写一篇300字左右的演讲词,并适当设计一些演讲技巧。
《贴邮票》活动要求:A、每组4人,给四封不同地点、质量的信件B、根据信封上的信息计算邮费并按要求贴上邮票(邮票的总面值刚好等于邮费,不能多贴)每封信最多贴三张邮票,只有0.8元或1.2元的两种邮票纪律要求:看看哪组合作得最好,速度最快!如果遇到困难,在事发那个在一边最后再去解决。3、小组汇报(1)、贴邮票的过程中大家遇到了什么问题?(有的能贴有的不能贴)这样的信件有哪些?(告诉我地点、质量、邮费)(2)、其他的信件都能贴出来嘛?说说看你是怎么贴邮票的?(3)、请将你们贴好邮票的信件送到邮箱来。剩下的都是一些“难题”(4)、思考:为什么4.0元、4.8元、6元的邮费没有办法按要求贴出邮票?(5)、原因出在哪里?这个问题怎么解决?(邮票面值太小,将邮票的面值改大)(6)、那最少要改成多大的?为什么?(将邮票面值改大,你会从多大面值的邮票开始考虑?为什么?)
Choose the best choice fromA to F to finish the dialogue. You have one more answer. Each choice should beused only once.A: Hello, I’m a schoolnewspaper reporter. May I ask you some questions?B: ____46____
B: It’s about theexperiments three astronauts are doing on the space station.A: That’s great. I’minterested in space, so I want to be an astronaut like them.
There are many kinds ___21___art forms in China. ___22___ you often see any of them in your life?They help us understand and enjoy the traditional Chinese culture. When theSpring Festival comes, some people often ___23___ the red paper intodifferent art works with scissors.
Tim: _______36_______,Bob.Bob: Good afternoon, Tim. Icalled you just now, but nobody answered. _______37_______?Tim: I went to the cinema.And I watched a movie named The Battle atLake Changjin.Bob: Oh, great. It’s very famous nowadays. _______38_______?
On a snowy day, there was a man walking in ahurry on the road. His clothes were in poor condition. You might think he was abeggar(乞丐),but in fact he was a painter. His name was Vincent Willem van Gogh.
I often use old clothes that people don’t wearany more to make bags. I opened a small shop in my community and set up awebsite to sell the bags online. Many customers think they are fantastic. Now Iplan to write a new book about ways to use old clothes.
Remember that it’s better to fail than it’s togive up, and the key is to learn from your failure(失败). But along withdifficulties, there will also be ____18____ wonderful waiting for you.
Michelle,a famous lady, has found that more than 25% students are too fat in hercountry. It is a very serious problem. So she starts a Health Program to dealwith it. The Health Program is to reduce the number of fat students today andin the future.
I often hear some students say English isdifficult, so they can’t learn it well. ___11___ English is very easy for me. I’m good ___12___ it. I’m very glad to tell you ___13___ about how I study English.
Theoil paper umbrella is a traditional Chinese handicraft(手工艺品).It has a history of over 1,000 years in China.In early TangDynasty, it was introduced to Japan and Korea, so it was called the “TangUmbrella”. Later oil paper umbrellas were spread to other Asian countries, suchas Vietnam, Thailand and Laos, and each had its own style. However, assteel-ribbed(钢骨的)umbrellas appeared in the last century, thehand-made oil paper umbrellas became less used in daily life. They were turnedinto decorative artifacts(装饰性工艺品).
___14___, I think an interest in Englishis very important. When I was in Grade Three, we had a new ___15___ — English,it was new for me. I was interested in it. I worked hard at it. Soon we had anEnglish exam and I got a very good mark. How ___16___ I was! After that,I learned English harder. Our English teacher often teaches us English songs,and ___17___ sound nice. I often think how interesting English is!
Bike-to-Work Day is held every year across North America on thethird Friday of May. It was started by the League of American Bicyclistsin 1956. Its aim is to promote (促进) the bicycle as a serious choice of getting toand from work. In today’s world where global warming is a serious issue, thebicycle is a perfect way of reducing our carbon (碳) footprint.
Bike-to-Work Day is held every year across NorthAmerica on the third Friday of May. It was started by the League ofAmerican Bicyclists in 1956. Its aim is to promote (促进) the bicycle as a seriouschoice of getting to and from work. In today’s world where global warming is aserious issue, the bicycle is a perfect way of reducing our carbon (碳) footprint.
Dealing with a nosebleed(鼻出血)mightseem simple. But recently, the British RED Cross asked parents with youngchildren how to help a child with a nosebleed. About 65 percent of parents didnot ____11____ the correct action to help.
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