(优化探究）2014高考数学总复习(人教A文)配套课件：8-7

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1、第七节　抛物线Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.一、抛物线的定义平面内与一个定点F和一条定直线l(定点F不在定直线l上)的距离的轨迹叫做抛物线，点F叫做抛物线的焦点，直线l叫做抛物线的．相等的

2、点准线Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyri

3、ght2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5Clien

4、tProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.[疑难关注]1．抛物线定义中定点的要求定点F不能在定直线l上，因为若定点F在定直线l上，则动点的轨迹为过点F且垂直于l的直线而非抛物线．2．抛物线方程y2＝2px中，只有当p>0时p有几何意义，且是抛物线的焦点到准线的距离．3．由y2＝mx(m≠0)或x2＝my(m≠0)求焦点坐标时，只需将x或y的系数除以4，再确定焦点位置即可．Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.

5、0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET

6、3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.解析：∵点P(2，y)在抛物线y2＝4x上，∴点

7、P到焦点F的距离等于点P到准线x＝－1的距离．∵点P到准线x＝－1的距离为3，∴点P到焦点F的距离为3.答案：BEvaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.Evaluationonly.CreatedwithAspose.Slidesfor.NET3.5ClientProfile5.2.0.0.Copyright2004-2011AsposePtyLtd.4．(课本习题改编)若抛物线的焦点在直线x－2

8、y－4＝0上，则抛物线的标准方程是________．解析：由x＝0