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1、,比例的意义和基本性质,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,1、什么叫做比？,两个数相除又叫做两个数的比。,2、什么叫做比值？,比的前项除以后项所得到的商，叫做比值。,一、复习回顾,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pt
2、y Ltd.,3、求出下列比的比值,12:16,4.5:2.7,：,10 : 6,=,=6,=,=,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,二、比例的意义,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,让我们一起来比较
3、一下天安门的国旗和教室里的国旗的长和宽的比有什么关系。,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,天安门的国旗： 5 : =,5m,5 ： = 60 ：40,m,60cm,40cm,教室里的国旗： 60 : 40 =,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004
4、-2011 Aspose Pty Ltd.,因为这两个比的比值相等，所以 5 ： = 60 ：40 也可以写成,像这样表示两个比相等的式子叫做比例。,=,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspos
5、e Pty Ltd.,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,三、比的基本性质,两个外项之积是2.440=,两个内项之积是1.660=,96,96,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,80 : 2,200 :
6、 5,内项,外项,5 : 3,10 : 6,内项,外项,400,400,30,30,805 2200,56 310,在比例里，两个外项的积等于两个内项的积。,这叫做比例的基本性质。,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,应用比例的基本性质判断下面的比例是否正确：,2. 6 ：3 = 8 ：5,3. 0.2 ：2.5 = 4 ：50,1. 2 ：3 = ：,4. 1.2 ：0.6 = 10 ：5,Eva
7、luation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,（对）,（错）,（对）,1、用比例的意义判断下面的比例是否正确：, 3 : 5 = 9 : 15, 2.5 : 5 = 25 : 0.5,四、反馈与巩固,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose P
8、ty Ltd.,B,C,B,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,9,3,5,5,3,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,5.下面每组中的四个数都可以组成 比例，把组成的比例写出来： （1）4、5、12和1
9、5。 （2）2、4 、5和10。,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,五、总结与归纳,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,课堂作业： 课本P36 2、5 家庭作业： 配套练习册P22P24,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,同学们再见！,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,
