练习课(第1-4课时).ppt

1、练习课（第14课时）,R四年级上册,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,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,状元成才路,状元成才路,状元成才路,一、复习旧知,认识线段、直线和射线,线段,直线,射线,有两个端点，不能向两端延伸。,没有端点，可以向两端无限延伸。,只有一个端点，只能向一端无限

2、延伸。,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,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,状元成才路,状元成才路,状元成才路,角的认识,从一点引出两条射线所组成的图形叫做角。,（ ）,（ ）,（ ）,顶点,边,边,角通常用符号“”来表示，上图的角可以记作“1”。,状元成才路,状元成才路,状元成才路

3、,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,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,角的度量,工 具,量角器,计量单位,度,步骤,量角器的中心与角的顶点重合。,0刻度线与角的一条边重合。,角的另一条边所对应的量角器上的刻度，就是这个角的度数。,状元成才路,状元成才路,状元成才路,状元成才路,状元成

4、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,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,认识平角和周角,定义,平角,一条射线绕它的端点旋转半周，形成的角叫做平角。,周角,一条射线绕它的端点旋转一周，形成的角叫做周角。,关系,1周角=2平角,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

5、,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,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, 画一条射线，使量角器的中心和射线的端 点重合，0刻度线和射线重合。, 在量角器相应度数刻度线的地方点一个点。, 以画出的射线的端点为端点，通过刚画的 点，再画一条射线。,画角的步骤,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

6、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,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,二、深化知识,1.（1）过一点O，能画直线吗？能画几条？,O,能画无数条,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

7、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,状元成才路,状元成才路,状元成才路,状元成才路,（2）过两点AB，能不能画直线？能画几条？,A,B,能画一条,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,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

8、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.下面说法对吗？对的在（ ）里画“”。 （1）直线是无限长的。（ ） （2）小于、等于90的角叫锐角。（ ） （3）将圆平均分成360份，人们把其中1份 所对的角作为角的单位。（ ）,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,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

9、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,3.看图填一填。,（1）已知1=70， 那么2=_.,（2）已知1=40， 那么2=_， 3=_， 4=_.,1,2,1,2,4,3,110,140,140,40,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,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,

10、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,三、巩固提高,1.判断：一条直线长10米。（ ）,直线可以向两端无限延伸，不能测量其长度。,2.判断：只要画角就必须用量角器。（ ）,一些特殊的角也可以用三角尺画。,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,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

11、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,1.用心选一选。(把正确答案的序号填在括号内) （1）线段有（ ）个端点。 A.1 B.2 C.无数 （2）通过一点，可以画（ ）条直线。 A.1 B.2 C、无数 （3）平角的两条边（ ） A.在一条直线上 B.在两条直线上 C.无法确定 （4）用一副三角板可以画出的角是（ ） A.160 B.40 C.120,B,C,C,A,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,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,状元成才路,状元成才路,状元成才路,填空：这是一个（ ）度的角。,120,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,