第1课时直线、射线、线段 (2)

单击此处编辑母版标题样式,单击此处编辑母版文本样式,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,单击此处编辑母版标题样式,单击此处编辑母版文本样式,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,4.2 直线、射线、线段第1课时 直线、射线、线段,R,七年级上册,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,推进新课,直线,知识点,1,思考,经过一点画直线，能画几条？经过两点呢？动手试一试,.,O,A,B,无数条,1,条,你能找出,生活中,应用,“,两点确定一条直线,”,原理的例子吗？,经过两点有一条直线，并且只有一条直线.即,两点确定一条直线,.,思考,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,砌墙时常在墙角分别固定一木桩，可以拉一条直的参照线,.,做家具时弹墨线,.,思考,为了便于说明和研究，我们应该如何表示一条直线？,1,可以用一个小写字母表示（如直线,l,）,.,2,因为,“,两点确定一条直线,”,，所以也可以用直线上的两点表示直线,.,A,B,l,判断下列语句是否正确：,.一条直线可以表示为“直线,A,”.,.一条直线可以表示为“直线,ab,”.,.一条直线既可以记为“直线,AB,”，又可以记为“直线,BA,”，还可以记为“直线,m,”.,思考,试着描述下图中点与直线的位置关系,.,a,点,O,在直线,l,上；点,P,不在直线,l,上,.,l,b,直线,l,经过点,O,；,直线,l,不经过点,P,.,O,P,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,点与直线的位置关系：,点在直线上（直线经过点）；点不在直线上（直线不经过点）,根据前面的讨论，你能总结出点与直线的位置关系吗？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,思考,我们应怎样描述,直线与直线之间的关系呢？,直线,a,和直线,b,相交于点,O,a,O,b,小结：,当两条不同的直线有一个公共点时，我们就称这两条直线,相交,，这个公共点叫做它们的,交点,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,强化练习,1.,用适当的语句描述图中点与直线的关系.,点,B,在直线,l,上；点,P,、,A,不在直线,l,上,.,点,A,在直线,b,、,c,交点上，点,B,在直线,a,、,b,交点上，点,C,在直线,a,、,c,交点上.,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,射线和线段,知识点,2,问题,射线和线段都是直线的一部分，类比直线的表示方法，怎样恰当的表示射线和线段呢？,A B,a,O A,l,线段,AB,或线段,a,射线,OA,或射线,l,思考,已知线段,AB,，你能由线段,AB,得到直线,AB,和射线,AB,吗？,1,2,把线段向两个方向无限延伸可得到直线,.,把线段向一个方向无限延伸可得到射线,.,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,判断下列说法是否正确：,a.,线段,AB,与射线,AB,都是直线,AB,的一部分.,b.,直线,AB,与直线,B,A,是同一条直线.,c.,射线,AB,与射线,BA,是同一条射线.,d.,端点重合的两条射线一定是同一条射线.,射线、线段都是直线的一部分；直线和射线不可度量.,根据前面的讨论，你能总结出直线、射线、线段之间的关系吗？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,强化练习,1,.,按下列语句画出图形：,a.点A在线段,MN,上b.射线,AB,不经过点,P,c.经过点,O,的三条线段,a,、,b,、,c,随堂演练,1.,下列语句准确规范的是（）,A.,直线,a,，,b,相交于一点,m,B.,延长直线,AB,C.,延长射线,AD,到点,B,(,A,是端点),D.,直线,AB,、,CD,相交于点,M,D,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,2.,在同一平面内有三个点,A,、,B,、,C,，过其中任意两个点画直线，可以画出的直线条数是多少？若过四个点,A,、,B,、,C,、,D,呢？,解：当,A,、,B,、,C,在同一直线上时，过其中任意两个点共可以作一条直线；当,A,、,B,、,C,不在同一直线上时，过其中任意两个点共可以作三条直线；当,A,、,B,、,C,、,D,在同一直线上时，过其中任意两个点共可以作一条直线；当,A,、,B,、,C,、,D,中有三个点在同一直线上时，过其中任意两个点共可以作四条直线；当,A,、,B,、,C,、,D,中均不在同一直线上时，过其中任意两个点共可以作六条直线.,课堂小结,没有端点,直线,平面图形,射线,线段,1,个端点,2,个端点,1.,从课后习题中选取；,2.,完成练习册本课时的习题。,课后作业,声 明,本文件仅用于个人学习、研究或欣赏，以及其他非商业性或非盈利性用途，但同时应遵守著作权法及其他相关法律的规定，不得侵犯本司及相关权利人的合法权利。,除此以外，将本文件任何内容用于其他用途时，应获得授权，如发现未经授权用于商业或盈利用途将追加侵权者的法律责任。,武汉天成贵龙文化传播有限公司,湖北山河律师事务所,