数学理科课件与练习数学第8章.ppt

第八章 圆锥曲线;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;1．动点P到定点F1(1,0)的距离比它到定点F2(3,0)的距离小2，则点P的轨迹是(　　) A．双曲线　　　　 　B．双曲线的一支 C．一条射线 D．两条射线 【解析】由条件，知|PF2|－|PF1|＝2，且|F1F2|＝3－1＝2，故点P的轨迹为一条射线． 【答案】　C ;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;/jty/main/index.shtm;【答案】　(1)D　　(2)B 【点评】(1)本例两道小题都用到双曲线的定义，熟练掌握双曲线定义和数形结合的思想非常重要；(2)与椭圆类似，解决双曲线中的焦点三角形问题的基本策略可概括为：紧扣双曲线的定义，结合正弦或余弦定理等解三角形知识，并在解答中合理使用方程和整体思想． 【变式与思考】(1)将(1)中条件改为“动圆M与圆C1：(x＋3)2＋y2＝4外切，同时与圆C2：x2＋y2－6x－91＝0内切”，试求动圆圆心M的轨迹方程；(2);/jty/main/index