2013年高中考试理科数学第一轮基本复习教学课件3.pptVIP

* * 第六节　椭　圆 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 1．椭圆的定义 平面内到两定点F1、F2的距离的和 _____________(大于|F1F2|)的点的轨迹叫椭圆． 集合P＝{M||MF1|＋|MF2|＝2a}，|F1F2|＝2c，其中a＞0，c＞0，且a，c为常数； (1)若_______________，则集合P为椭圆； (2)若_______________，则集合P为线段； (3)若_______________，则集合P为空集． 等于常数 2a＞|F1F2| 2a＝|F1F2| 2a＜|F1F2| Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 2．椭圆的标准方程和几何性质 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 性质 a、b、c间的关系 范围 对称性 顶点 离心率 ______≤x≤_____ _______≤y≤_____ 对称轴：________；对称中心：_______ A1(－a,0)，A2(a,0) B1(0，－b)，B2(0，b) e＝________∈(0,1) c2＝a2－b2 ______≤x≤____ _____≤y≤_____ A1(0，－a)，A2(0，a) B1(－b,0)，B2(b,0) －a a －b b －b b －a a 坐标轴 原点 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 1．椭圆的离心率的大小与椭圆的扁平程度有怎样的关系？ Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 【答案】　D Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 【解析】　如图，由椭圆的定义可知： |F1A|＋|F2A|＝2a＝8，|F1B|＋|F2B|＝2a＝8， ∴|AB|＝16－|F2A|－|F2B|＝6. 【答案】　6 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 Aspose Pty Ltd. 4．若一个椭圆长轴的长度、短轴的长度和焦距成等差数列，则该椭圆的离心率是________． Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 椭圆的定义及标准方程 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 Aspose Pty Ltd. 把①平方得|PF1|2＋|PF2|2＋2|PF1|·|PF2|＝4a2