2022年2019届高考数学考前归纳总结复习题2 .pdf





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1、圆锥曲线中的最值问题一、常见基本题型:(1)利用基本不等式求最值,例 1、已知椭圆两焦点1F、2F在y轴上,短轴长为2 2,离心率为22,P是椭圆在第一象限弧上一点,且121PFPF,过 P作关于直线F1P 对称的两条直线PA、PB分别交椭圆于 A、B两点,求PAB面积的最大值。解、设椭圆方程为22221yxab,由题意可得2,2,2 2abc,故椭圆方程为22142yx设AB的 直 线 方 程:mxy2.由142222yxmxy,得0422422mmxx,由0)4(16)22(22mm,得2222mP到AB的距离为3|md,则3|3)214(21|212mmdABSPAB2)28(81)8(
2、8122222mmmm。当且仅当22,222m取等号,三角形PAB面积的最大值为2。(2)利用函数求最值,例 2.如图,椭圆222:12xyCa的焦点在 x 轴上,左右顶点分别为1,A A,上顶点为 B,抛物线12,C C分别以 A,B 为焦点,其顶点均为坐标原点O,1C与2C相交于直线2yx上一点 P.(1)求椭圆 C及抛物线12,C C的方程;(2)若动直线l与直线 OP垂直,且与椭圆 C交于不同的两点 M,N,已知点(2,0)Q,求QM QN的最小值.解:(1)由题意(,0),(0,2)A aB,故抛物线 C1 的方程可设为axy42,C2的方程为yx242由xyyxaxy224422得
3、)28,8(,4 Pa所以椭圆C:121622yx,抛物线C1:,162xy抛物线C2:yx242(2)由(1)知,直线 OP的斜率为2,所以直线l的斜率为22设直线l方程为bxy22由bxyyx22121622,整理得0)168(28522bbxx因为动直线l与椭圆C 交于不同两点,所以0)168(2012822bb文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1
4、HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10
5、ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档
6、编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I
7、1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K1
8、0 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3
9、文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S
10、9I1 HR4N1I9Y7K10 ZC7B9L1A4V3解得1010b设 M(11,yx)、N(22,yx),则2121282816,55bxxb x x58)(2221)22)(22(2221212121bbxxbxxbxbxyy因为),2(),2(2211yxQNyxQM所以2)(2),2)(,2(2121212211yyxxxxyxyxQNQM5141692bb因为1010b,所以当98b时,QNQM取得最小值其最小值等于938514)98(516)98(592例3、已知抛物线)0(2:2ppyxC的焦点为F,抛物线上一点A的横坐标为1x)0(1x,过点A作抛物线C的切线1l交x轴于点D
11、,交y轴于点Q,交直线:2ply于点M,当2|FD时,60AFD(1)求证:AFQ为等腰三角形,并求抛物线C的方程;(2)若B位于y轴左侧的抛物线C上,过点B作抛物线C的切线2l交直线1l于点P,交直线l于点N,求PMN面积的最小值,并求取到最小值时的1x值解:(1)设),(11yxA,则切线AD的方程为pxxpxy2211,文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S
12、9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7
13、K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4
14、V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X
15、3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9
16、Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1
17、A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A
18、8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3所以),0(),0,2(11yQxD,12|ypFQ,所以|FAFQ,所以AFQ为等腰三角形且D为AQ中点,所以AQDF,60,2|AFDDF,12,60pQFD,得2p,抛物线方程为yx42(2)设)0(),(222xyxB,则B处的切线方程为22222xxxy由)4,2(42422121222211xxxxPxxxyxxxy,)1,22(14211211xxMyxxxy同理)1,22(22xxN,所以面积212211221221116)4)()41)(2222(21xxxxxxxxxxxxS设AB的方程为bkxy,则0b由04
19、4422bkxxyxbkxy,得代入得:bbkbbbbkS2222)1(64)44(1616,使面积最小,则0k,得到bbbS2)1(令tb,由得ttttttS12)1()(322,文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码
20、:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1
21、HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10
22、ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档
23、编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I
24、1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K1
25、0 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3文档编码:CR4A8X3S9I1 HR4N1I9Y7K10 ZC7B9L1A4V3222)1)(13()(ttttS,所以当)33,0(t时)(tS单调递减;当),
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