直线和圆的位置关系复习课教案

1、authority, jurisdiction has no criminal record issued by a police station and is willing to help the supervisory comments. up to now, the total handle pre-trial assessment 155, parole assessment 17, before litigation assessment 2. carry out unannounced inspections. in mid-may, community corrections

2、law enforcement brigade in 16 judicial district council conducted a flight inspection, focus on use, file management, specification of the platform implementation and to inform the analysis summary checks. successful completion of provincial vocational training organized by the office for social wor

3、k exam work. new released information management system training. 2014-criminal released personnel return to troubleshoot. first half of the year, the region today received community sentences of 211 people, lifting community corrections 235 people according to law, as of june 30, the scheduled comm

4、unity sentences of 484 people, including suspended for 425 people, 46 people on parole and temporary execution of 11 persons, control of 2. four, service development, to enhance legal services to boost the level of urban and rural construction. legal services cover work carried out. according to ton

5、g zheng (2013) 136th document requirements, paying careful attention to lawyers one to one legal services, insist on monthly inspection and the promotion of legal services cover work smoothly. further push four into four special legal service activities. formed sophisticated industry lawyer service

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7、f legal guarantees, continues to organization lawyer participation district government petition reception work, daily arrangements one lawyer participation petition duty work, effective maintenance normal of petition order, guarantees social harmony stable. developed jointly with the district prosec

8、utors office on the establishment of petition on procuratorial disputes resolution views of the lawyers intervention mechanism (for trial implementation), lawyers for the prosecutors office is equipped with a service team, for the petition on procuratorial disputes resolved to provide legal help. ho

9、jun xx spring breeze action. all district attorney launched a hojun xx week, the whole district attorney conducted voluntary legal advisory activities, in community law to provide legal services for residents of their communities, legal needs survey of businesses, community residents, providing advi

10、ce for the masses 86 passengers, issuing more than 200 copies of publicity materials. perfect the legal aid institution, especially speeding up the rural legal aid system . strengthening the construction of village-level legal assistance co-ordinators. through true strong legal aid liaison officers

11、at village level, where when people need legal aid, inform people applying for legal aid programs and materials required, guiding and helping the masses to the local legal aid station or apply to the legal aid centre. the first half, we cooperate with government involvement in xingren dream rai text

12、iles limited recourse over more than 300 workers labor compensation case, zhang zhi shan yun tong wood hundreds of recovery labor compensation case, riding a bank source city, casting plant, zhang zhi shan zhen hao dreams company enterprise labor compensation case直线和圆的位置关系复习课教案教学目标：通过对直线和圆的位置关系的复习，巩

13、固和掌握直线和圆的位置关系的判断方法及切线的判断和性质，切线长定理的运用，并灵活运用所学知识解决实践问题。 教学重点：直线和圆的位置关系的判断方法及切线的判断和性质，切线长定理。 教学难点：运用直线和圆的位置关系的判断方法及切线的判断和性质，切线长定理的解题。一旧知回顾一、直线和圆的位置关系“大漠孤烟直，长河落日圆” 是唐朝诗人王维的诗句，它描述了黄昏日落时分塞外特有景象。请观察图中日落的情景, 根据直线与圆的公共点的个数回顾一下，直线和圆的位置关系有几种？根据日落的情景填出下列表格图形直线和圆的位置关系相交相切相离交点个数2个1个0个圆心距d和半径r之间的关系drd=rdr规律总结： 我们可

14、以从两个方面去判断直线和圆的位置关系 （1）根据直线和圆的公共点的个数 （2）根据圆心到直线的距离和半径之间的数量关系填空：考题再现1、（2007福建）如图，把太阳看成一个圆，则太阳与地平线a的位置关系是 -. （填相交、相切、相离）2、已知o的直径是11cm，点o到直线a的距离是5.5cm，则o与直线a的位置关是 _ _;直线a与o的公共点个数是_.3、已知：圆的半径等于10厘米，直线a和圆有唯一的公共点，则圆心到直线a的距离是 厘米二：切线的判定定理问题1：如图点a是o上一点， oa是o的半径，aboa垂足为a，则ab是o的-.切线的判定定理：经过半径外端并且垂直于这条半径的直线是圆的切线

15、。问题2：如图ab是o的切线，点a是o上的一点则 ab _ oa 切线的性质： 圆的切线垂直于经过切点的半径.三：切线长定理如图，p是o外一点，pa，pb是o的两条切线， 线段pa，pb叫做点p到o的-. pa - pb。连接op，则apo_ bpo切线长定理：从圆外一点引圆的两条切线，它们的切线长相等，这一点和圆心的连线平分两条切线的夹角。如图：（1）ab、ac、bc是o的切线，切点分别是d、e、f，请找出图中相等的线段 (1) (2)（2）移动ac到如图所示的位置,请找出图中相等的线段。并观察abc的周长与切线长bd、bf的关系.填空：、（2007浙江）如图：pa切o于点a，该圆的半径为3

16、，po=5，则pa的长等于-. .、（孝感）如图：、是o上的两点，是o的切线，则-. 3、已知：如图,pa、pb是o的切线，切点分别是a、b，q为o上一点，过 q点作o的切线，交pa、pb于e、f点，已知pa=12cm， 则pef的周长-. 二：考题再现 例1（2007年泸州）已知ab是o的直径，bc是o的切线，切点为b，oc平行于弦ad求证：dc是o的切线例2.如右图所示，已知oc平分aob，d是oc上任意一点，d与oa相切于点e。那么，ob是d的切线吗？请说明理由。 规律总结:证明一条直线是圆的切线,常常要添加辅助线,如果直线与圆有一个公共点,则连接这点和圆心,证明直线垂直于经过这点的半径

17、；如果直线和圆没有公共点，则过圆心作直线的垂线，证明圆心到直线的距离等于半径。三.当堂测评：1、已知 rtabc的斜边ab=6cm,直角边ac=3cm,以点c为圆心，半径分别为cm和4cm画两个圆，这两个圆与ab有怎样的位置关系？当半径为多长时，ab与圆c相切？2、如图所示，ab为o的直径，c是o上的一点，d在ab的 延长线上，dcb= a。求证：cd是o的切线 四.课堂小结： 1 今天我们一起复习哪些圆的有关知识？2 今天我们探究的问题都有什么特点？3 今天你有什么收获吗？ 五课后作业：1.已知ab是o的直径，bc是o的切线，切点为b，oc平行于弦ad求证：dc是o的切线 2.设c线段ab的

18、中点，四边形bcde是以bc为一边的正方形。作以b为圆心，bd长为半径的圆b,连接ad。求证：ad是圆b的切线of recourse. effective safeguarding workers legitimate rights. increase legal aid efforts. visit for assistance cases, discover problems in the adjustment. legal aid advocacy, from three aspects of broad, vivid and persistent, using a variety of

19、 channels, in various forms, highlighting key, step up publicity, build public understanding of legal assistance, support, legal assistance, legal aid society. in january-june, the notary office for various types of notarization of 1577. first half of judicial legal assistance centre had 530 for all

20、 kinds of legal aid cases, of which 489, 41 criminal cases civil cases, answer legal consultants received over more than 9,800, free legal services cost more than 476,000 yuan, for the parties to be compensated more than 8.21 million yuan. handling mass cases, 6 involved migrant workers, 418. consul

21、tant unit established by the region-wide grass-roots legal services has amounted to 789, region-wide grass-roots legal workers to handle cases of 1197, avoid and recover 54.78 million yuan of economic loss. five, optimization style, to enhance the overall image of the administration of justice. inte

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