第2课时 方格纸上图形的旋转变换.ppt

1、,第 2 课时 方格纸上图形的旋转变换,R五年级下册,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,图形1绕O点顺时针旋转90，可得到图形（ ）所在位置；,回顾复习,O,2,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,图形2绕O点顺时针旋转90，可得到图形（

2、 ）所在位置；,O,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,图形2绕O点逆时针旋转（ ），可得到图形4所在位置；,O,180,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,如果将上述图形固定在方格纸中，你还能说一说图形的位置怎样变化？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,如图，将直角三

3、角尺固定在方格纸上， 像这样在方格纸上每次顺时针方向旋转 90，观察三角尺的位置是如何变化的。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,你有什么发现？,我发现旋转时O点的位置不变。,每旋转一次，三角尺的两条直角边都绕点O顺时针旋转了 90。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状

4、元成才路,状元成才路,状元成才路,换另一把三角尺，在方格纸上按逆时针方向像前面那样转一圈并说一说。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,画出三角形 AOB 绕点 O 顺时针旋转90后的图形。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,A,B,O,

5、绕点 O 旋转，点O的位置应该不变。只要找出点 A 和点B 顺时针旋转 90后的位置,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,A,B,A,先画 OA，OA 顺时针旋转 90后的位置 OA，OA垂直于 OA，点 A与点 O 的距离应该是4格。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,A,B,A,B,再画 OB，OB 顺时针旋转 90后的位置 OB，OB垂直于 OB，点 B与点 O 的距离应该

6、是 3格。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,A,B,A,B,连接 AB，三角形 AO B就是AOB 绕点 O 顺时针旋转 90后的图形。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,你能在方格纸上画出三角形AOB 绕点O 逆时针旋转 90后的图形吗？,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

7、成才路,连接 AB，三角形 AO B就是AOB 绕点 O 逆时针旋转 90后的图形。,再画 OB，OB 逆时针旋转 90后的位置 OB，OB垂直于 OB，点 B与点 O 的距离应该是3格。,先画 OA，OA 逆时针旋转 90后的位置 OA，OA垂直于 OA，点 A与点 O 的距离应该是4格。,A,B,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,怎样画出简单图形旋转90后的图形？,（1）找出图形的关键点或线段。 （2）借助三角尺作原图形的线段或关键点与旋转中心所在线段的垂线。 （3）在所画垂线上量

8、出与原线段相等的长度。 （4）顺次连接所画出的对应点。,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,巩固提升,1.,（1）图形OABC绕点O顺时针旋转90，在右图中标出点A的对应点A 。,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,（2）图形OABC绕点O顺时针旋转（ ），得到图2。,180,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成

9、才路,状元成才路,状元成才路,状元成才路,（1）把图 1 绕点O逆时针旋转90后得到图2 。 （2）把图1绕点O顺时针旋转90后得到图3 。 （3）把图2 绕点O逆时针旋转90后得到图 4 。 （4）把图1 、图2、图3、图4 都涂上红色，这个图形像什么？,2. 按要求画图。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,1,2,3,4,这是主题图中荷兰风车的形状哦！,3.如图，长方形的两条对称轴相交于点 O 。,旋转90,旋转180,旋转360,状元成才路,状元成才路,状元成才路,状元成才路,状

10、元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,问题：按上面的方法试一试，你发现下面的图形有什么特点？,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,旋转90,旋转180,旋转360,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,旋转90,旋转180,旋转360,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路

11、,状元成才路,状元成才路,状元成才路,状元成才路,旋转90,旋转180,旋转360,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,旋转90,旋转180,旋转360,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,说说你的收获吧！,课后作业,1. 课本P86，第5题； 2. 完成练习册本课时的习题。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路