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1、2009年下学期湖南长郡卫星远程学校制作 09Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09二、讲授新课:1. 椭圆定义:平面内与两个定点F
2、1F2的距离和等于常数(大于|F1F2|)的点的轨迹叫作椭圆,这两个定点叫做椭圆的焦点,两焦点间的距离叫做椭圆的焦距。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长
3、郡卫星远程学校制作 09求动点轨迹方程的一般步骤:(1) 建立适当的坐标系,用有序实数对(x, y)表示曲线上任意一点M的坐标; (2) 写出适合条件 P(M); (3) 用坐标表示条件P(M),列出方程; (4) 化方程为最简形式; (5) 证明以化简后的方程为所求方程(可以省略不写,如有特殊情况,可以适当予以说明)Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Clie
4、nt Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 092. 求椭圆的方程: 探讨建立平面直角坐标系的方案由椭圆的定义得, 限制条件:设M(x, y)是椭圆上任意一 点,椭圆的焦距2c(c0), M 与F1和F2的距离的和等于 正常数2a (2a2c), 则F1、F2 的坐标分别是(-c,0)、(c,0).法1: 取过焦点F1、F2的直线为x轴, 线段F1F2的 垂直平分线为y轴, 建立平面直角坐标系(如图).Evaluati
5、on only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09叫做椭圆的标准方程。Evaluation only.Evaluation only. Created with
6、 Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 093. 椭圆的标准方程:焦点在x轴:焦点在y轴:Evaluation only.Evaluation only. Created with Aspose.Slides for .NET
7、3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09定 义|MF1|+|MF2|=2a(2a2c0)图 形方 程焦 点 a,b,c之 间的关系Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.
8、5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09定 义|MF1|+|MF2|=2a(2a2c0)图 形方 程焦 点 a,b,c之 间的关系OxMF2F1yEvaluation only.Evaluation only. Created with Aspose.Slides for .
9、NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09定 义|MF1|+|MF2|=2a(2a2c0)图 形方 程焦 点 a,b,c之 间的关系yMF2F1xOOxMF2F1yEvaluation only.Evaluation only. Created with Aspos
10、e.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09定 义|MF1|+|MF2|=2a(2a2c0)图 形方 程焦 点 a,b,c之 间的关系yMF2F1xOOxMF2F1yEvaluation only.Evaluation only. Crea
11、ted with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09定 义|MF1|+|MF2|=2a(2a2c0)图 形方 程焦 点 a,b,c之 间的关系yMF2F1xOOxMF2F1yEvaluation only.Evaluat
12、ion only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09定 义|MF1|+|MF2|=2a(2a2c0)图 形方 程焦 点F(c, 0) a,b,c之 间的关系yMF2F1xOOxMF2F1yEv
13、aluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09定 义|MF1|+|MF2|=2a(2a2c0)图 形方 程焦 点F(c, 0)F(0, c) a
14、,b,c之 间的关系yMF2F1xOOxMF2F1yEvaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09定 义|MF1|+|MF2|=2a(2a2
15、c0)图 形方 程焦 点F(c, 0)F(0, c) a,b,c之 间的关系c2=a2b2(ac0,ab0)yMF2F1xOOxMF2F1yEvaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.
16、2009年下学期湖南长郡卫星远程学校制作 09例1 下列各式哪些表示椭圆?若是,则判定其焦点在何轴?并指明a2,b2,写出焦点坐标.Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2009年下学期湖南长郡卫星远程学校制作 09例2 求适合下列条件的椭圆的标准方程:(1) a= ,b=1,焦点在x轴上;(2) 焦点为F1(0,3),F2(0,3),且a=5;(3) 两个焦点分别是F1(2,0)、F2(2,0),且过P(2