中考数学必考知识点：平移与旋转.doc

中考数学必考知识点：平移与旋转知识点回顾知识点一：平移变换的概念由一个图形改变为另一个图形，在改变的过程中，原图形上所有的点都沿 方向运动，且运动 的距离，这样的图形改变叫做图形的平移变换，简称平移.例1：如图所示，A，B，C，D四个图形中可以由图形E平移得到的是图形（ ） 答案：C .同步测试：1. 如图2中的两个福娃贝贝，其中左边的福娃贝贝可以看作是右边的福娃贝贝经过 得到的.答案：平移2. 学校对学生寝室进行了整顿，并举行了文明寝室评比，结果七年级（1）班被评为文明寝室.你看她们的牙刷、牙杯放得多整齐，你能说说她们用了数学知识中的 .答案：平移变换.知识点二：平移变换的性质平移变换不改变图形的 、 和 .连结对应点的线段平行（或在同一条直线上）而且 .例2：网格中有一个小甲虫（），它喜欢吃牛粪，它又会把吃剩的牛粪滚成牛粪球（）藏进仓库（）.规定向左为L，向右为R，向上为U，向下D，如：L1表示向左平移一格，D2表示向下平移2格.例如：要把左图中的所有的牛粪球推到最近的仓库里，可以编写程序：L1-R1-U2-D3-R2-U1，小甲虫就能把所有的牛粪球推到最近的仓库.你来试一试，可编写一个怎样的程序才能使小甲虫把右边图上的所有牛粪球推到最近的仓库里.（只需写出一种可行的程序即可） 答案：答案不唯，如R1-U2-D1-L1-D1-R2-D1-R1-U1.同步测试：将长度为6cm的线段向上平移14cm，所得线段的长度是（ ） A.6cm B.18cmC.14cm D.10cm答案：A.知识点三：旋转变换的概念由一个图形改变为另一个图形，在改变的过程中，原图形上的所有点都绕一个 的点，按同一个 ，转动同一个角度，这样的图形改变叫做图形的旋转变换，简称旋转，这个固定的点叫做 中心.例3关于旋转变换下列说法正确的有（ ）旋转变换不改变图形的形状；旋转变换不改变图形的大小；旋转变换不改变图形的位置；旋转变换的旋转角度相等，旋转的结果就一样(A)1个 (B)2个 (C)3个 (D)4个答案：B.同步测试：1.在下列图形中，可以通过部分旋转后得到的图形是（ ）答案：A.知识点四：旋转变换的性质旋转变换不改变图形的 和大小。对应点到旋转中心的距离 。对应点与旋转中心连线所成的角度 旋转的角度。例4（2008年双柏县中考题）如图是某设计师在方格纸中设计图案的一部分，请你帮他完成余下的工作：（1）作出关于直线AB的轴对称图形；（2）将你画出的部分连同原图形绕点O逆时针旋转；（3）发挥你的想象，给得到的图案适当涂上阴影，让它变得更加美丽解：如图（涂阴影略）随堂检测1. 屋檐最前端的一片瓦为瓦当，瓦面上带著有花纹垂挂圆型的挡片。下列例举了四种瓦当，其中是轴对称图形的有（ ）A.1种 B.2种 C.3种 D.4种2. 如图，若，边绕点逆时针旋转后能构成平角，则（ ）（）（）（）（）3. 如图，边长相等的两个正方形ABCD和OEFG，若将正方形OEFG绕点O按逆时针方向旋转130，两个正方形的重叠部分四边形OMCN的面积（ ）A不变B先增大再减小C先减小再增大D不断增大4. 如图，四边形EFGH是由四边形ABCD平移得到的，已知AD=5，B=70，则（）AFG=5，G=70BEH=5，F=70CEF=5， F=70DEF=5， E=705. 如图，将网格中的三条线段沿网格线平移后组成一个首尾相接的三角形，至少需要移动_格6. 钟表的分针旋转120所需时间为分；时针转3小时，旋转了7. 一块长方形草地的大小尺寸如图所示，要在上面沿东西、南北方向分别铺2条、4条甬道，若甬道的宽均为1米，则草地的总面积为8. 四边形是正方形，旋转后与重合。（1）旋转中心是哪一点？（2）旋转角等于多少度？（3）试判断的形状。9. 如图一块三角形的玻璃裂开成A、B、C共3块，位置、形状如图所示，请选择若干次平移变换、轴对称变换把它复原成整个三角形，请简明扼要地讲述你所做的变换过程。10如图，魔术师把4张扑克牌放在桌子上，如图（1），然后蒙住眼睛，请一位观众上台把某一张牌旋转180，魔术师解开蒙具后，看到四张牌如图（2）所示，他很快确定了哪一张牌被旋转过，你能说明其中的奥妙吗？答案随堂检测：1.C 2.B 3.A 4.B 5.9 6. 20，90 7. 224平方米 8. （1）旋转中心是B点；（2）旋转角等于90度；（3）等腰三角形9. 将沿第一条水平实线作轴对称变换，再向上平移一格，向右平移三格，向左平移格，就可以拼成三角形10图（1）与图（2）中扑克牌完全一样，说明被旋转过的牌是旋转180后与原来相同，而图中只有方块4是符合，故方块4被旋转过 技术官员村位于位于亚运城东部，主干道二以东石楼涌以西的地块，占地面积、m2，总建筑面积、m2，共包括地下室南区、地下室北区、地上部分1栋12栋、服务中心、室外工程等多个单体工程。其中住宅面积m2，共12栋，17栋建筑层数为11层，812栋11层（局部复式顶层），首层局部架空，布置公建配套设施。integrated energy, chemicals and textile Yibin city, are the three core pillars of the industry. In 2014, the wuliangye brand value to 73.58 billion yuan, the citys liquor industry slip to stabilise. Promoting deep development of integrated energy, advanced equipment manufacturing industry, changning district, shale gas production capacity reached 277 million cubic metres, built the countrys first independent high-yield wells and pipelines in the first section, the lead in factory production and supply to the population. 2.1-3 GDP growth figure 2.1-4 Yibin, Yibin city, Yibin city, fiscal revenue growth 2.1.4 topography terrain overall is Southwest, North-Eastern State. Low mountains and hills in the city landscape as the main ridge-and-Valley, pingba small fragmented nature picture for water and the second land of the seven hills. 236 meters to 2000 meters above sea level in the city, low mountain, 46.6% hills 45.3%, pingba only 8.1%. 2.1.5 development of Yibin landscapes and distinctive feature in the center of the city, with limitations, and spatial structure of typical zonal group, 2012-cities in building with an area of about 76.2km2. From city-building situation, old town-the South Bank Center construction is lagging behind, disintegration of the old city is slow, optimization and upgrading, quality public service resources are still heavily concentrated in the old town together. Southbank Centre has not been formed, functions of the service area space is missing. Meanwhile, peripheral group centres service was weak and inadequate accounting for city development, suspicious pattern could not be formed. As regards transport, with the outward expansion of cities, cities have been expanding, centripetal city traffic organization has not changed, integrated energy, chemicals and textile Yibin city, are the three core pillars of the industry. In 2014, the wuliangye brand value to 73.58 billion yuan, the citys liquor industry slip to stabilise. Promoting deep development of integrated energy, advanced equipment manufacturing industry, changning district, shale gas production capacity reached 277 million cubic metres, built the countrys first independent high-yield wells and pipelines in the first section, the lead in factory production and supply to the population. 2.1-3 GDP growth figure 2.1-4 Yibin, Yibin city, Yibin city, fiscal revenue growth 2.1.4 topography terrain overall is Southwest, North-Eastern State. Low mountains and hills in the city landscape as the main ridge-and-Valley, pingba small fragmented nature picture for water and the second land of the seven hills. 236 meters to 2000 meters above sea level in the city, low mountain, 46.6% hills 45.3%, pingba only 8.1%. 2.1.5 development of Yibin landscapes and distinctive feature in the center of the city, with limitations, and spatial structure of typical zonal group, 2012-cities in building with an area of about 76.2km2. From city-building situation, old town-the South Bank Center construction is lagging behind, disintegration of the old city is slow, optimization and upgrading, quality public service resources are still heavily concentrated in the old town together. Southbank Centre has not been formed, functions of the service area space is missing. Meanwhile, peripheral group centres service was weak and inadequate accounting for city development, suspicious pattern could not be formed. As regards transport, with the outward expansion of cities, cities have been expanding, centripetal city traffic organization has not changed,