例2求和圆O:x2+y2=1外切，且和直线x=-1相切的动圆圆心C的轨迹方程。,设：动圆圆心C（x,y)，半径为r。,解：,则有|OC|=r+1,而r=|x+1|,从而得|OC|=|x+1|+1,化简得：当x-1时，y2=4(x+1) 当x-1时，y=0,从一道例题引发的思考:,想没想过考虑直线l:x=-2 ?,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,“定义法”求轨迹方程,圆锥曲线专题复习1,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,所以，动圆心的轨迹是以O1、O2为焦点，2a=12的椭圆,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,定义法求轨迹方程的一般步骤:,一 定 型,二 定 位,三 定 方 程,四 定 范 围,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,（点F不在l上）,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,在平面内 ,讨论：,圆,椭圆,除去长轴两端点,双曲线的右支,抛物线,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,A,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.,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.,小结,Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.,