高中数学必修2第2章抛物线的参数方程知识点
2017-06-14
在高中数学遇到需要解决的与抛物线有关的问题时,同学们需要牢记它的方程,下面是小编给大家带来的高中数学必修2第2章抛物线的参数方程知识点,希望对你有帮助。
高中数学抛物线的参数方程知识点(一)
抛物线方程
1 设,抛物线的标准方程、类型及其几何性质:
图形
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/00260214I-0.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602C27-1.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602B62-2.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026022929-3.gif)
焦点
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026023219-4.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602G61-5.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026022940-6.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026024506-7.gif)
准线
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026024637-8.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026025A5-9.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026022210-10.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026024050-11.gif)
范围
对称轴轴轴
顶点 (0,0)
离心率
焦点
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026023105-12.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026026146-13.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026022300-14.gif)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026023532-15.gif)
注:①顶点
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026024119-16.gif)
.
②则焦点半径
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026023109-17.gif)
;则焦点半径为
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026021Q7-18.gif)
.
③通径为2p,这是过焦点的所有弦中最短的.
④(或)的参数方程为
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026024291-19.gif)
(或
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026024327-20.gif)
)(为参数).
高中数学抛物线的参数方程知识点(二)
抛物线的性质(见下表):
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/00260211Y-21.gif)
抛物线的焦点弦的性质:
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/00260245E-22.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602J38-23.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026024532-24.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602A32-25.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026024V7-26.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602E35-27.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/00260224a-28.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/00260241Q-29.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602L05-30.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026022T6-31.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026023336-32.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602K01-33.jpg)
关于抛物线的几个重要结论:
(1)弦长公式同椭圆.
(2)对于抛物线y2=2px(p>0),我们有P(x0,y0)在抛物线内部
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/00260232C-34.jpg)
P(x0,y0)在抛物线外部
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026022T6-35.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026025I7-36.jpg)
(3)抛物线y2=2px上的点P(x1,y1)的切线方程是
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602DD-37.jpg)
抛物线y2=2px(p>0)的斜率为k的切线方程是y=kx+
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602D63-38.jpg)
(4)抛物线y2=2px外一点P(x0,y0)的切点弦方程是
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/002602K10-39.jpg)
(5)过抛物线y2=2px上两点
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026025Y6-40.jpg)
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026022292-41.jpg)
的两条切线交于点M(x0,y0),则
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026022460-42.jpg)
(6)自抛物线外一点P作两条切线,切点为A,B,若焦点为F,
![](http://xue.xueersi.com//i2.sanwen.net/doc/161208/0026021b7-43.jpg)
又若切线PA⊥PB,则AB必过抛物线焦点F.