ËùÒÔb£½2£¬ËùÒÔÍÖÔ²µÄ±ê×¼·½³ÌΪ£«£½1.
32(2)¢Ùµ±Ö±ÏßBDµÄбÂÊk´æÔÚÇÒk¡Ù0ʱ£¬ Ö±ÏßBDµÄ·½³ÌΪy£½k(x£«1)£¬ ´úÈëÍÖÔ²·½³Ì£«£½1£¬
32
²¢»¯¼òµÃ(3k£«2)x£«6kx£«3k£6£½0.
2
2
2
2
2
x2y2
x2y2
¦¤£½36k£4(3k£«2)(3k£6)£½48(k£«1)>0ºã³ÉÁ¢£® ÉèB(x1£¬y1)£¬D(x2£¬y2)£¬
6k3k£6
Ôòx1£«x2£½£2£¬x1x2£½2£¬
3k£«23k£«2|BD|£½1£«k¡¤|x1£x2|
43(k£«1)
£½(1£«k)¡¤[?x1£«x2?£4x1x2]£½. 2
3k£«2
2
2
2
22
2
4222
1
ÓÉÌâÒâÖªACµÄбÂÊΪ££¬
k?1?43?2£«1?2?k?43(k£«1)
ËùÒÔ|AC|£½£½. 2
12k£«33¡Á2£«2
k|AC|£«|BD|£½43(k£«1)?
2
2
?21£«21?
??3k£«22k£«3?
2
22
203(k£«1)203(k£«1)£½¡Ý (3k2£«2)(2k2£«3)?(3k2£«2)£«(2k2£«3)?2
??
2??
203(k£«1)163
£½£½. 22
25?k£«1?5
4
2
2
µ±ÇÒ½öµ±3k£«2£½2k£«3£¬¼´k£½¡À1ʱ£¬ÉÏʽȡµÈºÅ£¬ 163
¹Ê|AC|£«|BD|µÄ×îСֵΪ. 5¢Úµ±Ö±ÏßBDµÄбÂʲ»´æÔÚ»òµÈÓÚÁãʱ£¬ 103163
¿ÉµÃ|AC|£«|BD|£½>. 35163
×ÛÉÏ£¬|AC|£«|BD|µÄ×îСֵΪ.
5
2£®(2018¡¤ÖîôßÊÐÊÊÓ¦ÐÔ¿¼ÊÔ)ÒÑÖªFÊÇÅ×ÎïÏßC£ºx£½2py(p>0)µÄ½¹µã£¬¹ýFµÄÖ±Ïß½»Å×ÎïÏßCÓÚ²»Í¬µÄÁ½µãA(x1£¬y1)£¬B(x2£¬y2)£¬ÇÒx1x2£½£1.
13
2
22
(1)ÇóÅ×ÎïÏßCµÄ·½³Ì£»
(2)¹ýµãB×÷xÖáµÄ´¹Ïß½»Ö±ÏßAO(OΪ×ø±êÔµã)ÓÚµãD£¬¹ýµãA×÷Ö±ÏßDFµÄ´¹ÏßÓëÅ×ÎïÏßCµÄÁíÒ»½»µãΪE£¬AEµÄÖеãΪG. ¢ÙÇóµãDµÄ×Ý×ø±ê£» ¢ÚÇó|GB||DG|µÄÈ¡Öµ·¶Î§£®
½â (1)ÉèAB£ºy£½kx£«p2
£¬
?ÁªÁ¢??
y£½kx£«p2£¬2
p??x2£½2py£¬
µÃx£½2p??
?
kx£«2???£¬
¼´x2
£2pkx£p2
£½0£¬ ¡àx2
1x2£½£p£½£1£¬¡àp£½1£¬ ¡àÅ×ÎïÏßCµÄ·½³ÌΪx2
£½2y. (2)¢ÙÖ±ÏßOAµÄ·½³ÌΪy£½y1x1
xx£½x£¬
12¡àD??
xx1x2?
2£¬
2???£¬¼´D???
x12£¬£2???£¬ ¡àµãDµÄ×Ý×ø±êΪ£1
2.
¢Ú¡ßk1
DF£½£x£¬¡àkAE£½x2£¬
2
¼´Ö±ÏßAEµÄ·½³ÌΪy£y1£½x2(x£x1)£¬
?y£y1£½x2?x£x1?£¬ÁªÁ¢??x2
2
£x2x£y1£1£½0£¬
??y£½x2
2
£¬
µÃ¡àxE£½2x2£x1£¬¡àG(x2,2y2£«y1£«1)£® ¡àG£¬B£¬DÈýµã¹²Ïߣ¬¡à|GB|y2£«y1£«1
|DG|£½2y3
£¬
2£«y1£«
2¡ßy1
1¡¤y2£½4
£¬
|DG|y1
1£«
¡à
2
|GB|£½2£1£½2£y1
4y£«y1
1£«1y1£«12
14
1
£½2£¡Ê(1,2)£¬
11£«2y1¡à
|GB|?1?
¡Ê?£¬1?. |DG|?2?
3£®(2018¡¤È«¹ú¢ó)ÒÑ֪бÂÊΪkµÄÖ±ÏßlÓëÍÖÔ²C£º£«£½1½»ÓÚA£¬BÁ½µã£¬Ï߶ÎABµÄ
43ÖеãΪM(1£¬m)(m>0)£® 1
(1)Ö¤Ã÷£ºk<££»
2
¡ú¡ú¡ú¡ú¡ú¡ú
(2)ÉèFΪCµÄÓÒ½¹µã£¬PΪCÉÏÒ»µã£¬ÇÒFP£«FA£«FB£½0.Ö¤Ã÷£º|FA|£¬|FP|£¬|FB|³ÉµÈ²îÊýÁУ¬²¢Çó¸ÃÊýÁеĹ«²î£®
(1)Ö¤Ã÷ ÉèA(x1£¬y1)£¬B(x2£¬y2)£¬ Ôò£«£½1£¬£«£½1. 4343Á½Ê½Ïà¼õ£¬²¢ÓÉÓÉÌâÉèÖª
x2y2
x2y211x2y222
y1£y2x1£«x2y1£«y2
£½k£¬µÃ£«¡¤k£½0. x1£x243
y1£«y2
2
3
£½m£¬ÓÚÊÇk£½£.¢Ù
4mx1£«x2
2
£½1£¬
31
ÓÉÌâÉèµÃ0 (2)½â ÓÉÌâÒâµÃF(1,0)£®ÉèP(x3£¬y3)£¬Ôò (x3£1£¬y3)£«(x1£1£¬y1)£«(x2£1£¬y2)£½(0,0)£® ÓÉ(1)¼°ÌâÉèµÃx3£½3£(x1£«x2)£½1£¬ y3£½£(y1£«y2)£½£2m<0. 3 ÓÖµãPÔÚCÉÏ£¬ËùÒÔm£½£¬ 43?¡ú3?´Ó¶øP?1£¬£?£¬|FP|£½£¬ 2?2?¡ú22 ÓÚÊÇ|FA|£½?x1£1?£«y1£½ x1?x1??x1£1?£«3?1£?£½2£. 2?4? 2 2 x2¡ú ͬÀí|FB|£½2£. 2 1¡ú¡ú ËùÒÔ|FA|£«|FB|£½4£(x1£«x2)£½3. 2 ¡ú¡ú¡ú¡ú¡ú¡ú ¹Ê2|FP|£½|FA|£«|FB|£¬¼´|FA|£¬|FP|£¬|FB|³ÉµÈ²îÊýÁУ® 11¡ú¡ú2Éè¸ÃÊýÁеĹ«²îΪd£¬Ôò2|d|£½||FB|£|FA||£½|x1£x2|£½?x1£«x2?£4x1x2.¢Ú 22 15 3 ½«m£½´úÈë¢ÙµÃk£½£1£¬ 4 7 ËùÒÔlµÄ·½³ÌΪy£½£x£«£¬´úÈëCµÄ·½³Ì£¬ 412 ²¢ÕûÀíµÃ7x£14x£«£½0. 4 1321 ¹Êx1£«x2£½2£¬x1x2£½£¬´úÈë¢Ú½âµÃ|d|£½. 2828321321 ËùÒÔ¸ÃÊýÁеĹ«²îΪ»ò£. 2828 12 4.(2018¡¤¼ÎÐËÊС¢ÀöË®ÊнÌѧ²âÊÔ)µãP(1,1)ΪÅ×ÎïÏßy£½xÉÏÒ»¶¨µã£¬Ð±ÂÊΪ£µÄÖ±Ïß 2ÓëÅ×ÎïÏß½»ÓÚA£¬BÁ½µã£® (1)ÇóÏÒABÖеãMµÄ×Ý×ø±ê£» (2)µãQÊÇÏ߶ÎPBÉÏÈÎÒâÒ»µã(ÒìÓڶ˵ã)£¬¹ýQ×÷PAµÄƽÐÐÏß½»Å×ÎïÏßÓÚE£¬FÁ½µã£¬ÇóÖ¤£º|QE|¡¤|QF|£|QP|¡¤|QB|Ϊ¶¨Öµ£® (1)½â kAB£½ yA£yB11 £½£½££¬(*) xA£xByA£«yB2 yA£«yB2 £½£1. ËùÒÔyA£«yB£½£2£¬yM£½ (2)Ö¤Ã÷ ÉèQ(x0£¬y0)£¬Ö±ÏßEF£ºx£x0£½t1(y£y0)£¬ Ö±ÏßPB£ºx£x0£½t2(y£y0)£¬ ÁªÁ¢·½³Ì×é? 2 ??x£x0£½t1?y£y0?£¬??y£½x£¬ 2 µÃy£t1y£«t1y0£x0£½0£¬ ËùÒÔyE£«yF£½t1£¬yE¡¤yF£½t1y0£x0£¬ |QE|¡¤|QF|£½1£«t1|yE£y0|¡¤1£«t1|yF£y0| £½(1£«t1)|y0£x0|. ͬÀí|QP|¡¤|QB|£½(1£«t2)|y0£x0|. 2 2 2 2 22ÓÉ(*)¿ÉÖª£¬t1£½ 1 kEFkPA£½1 £½yA£«yP£¬t2£½1 kPB£½yB£«yP£¬ ËùÒÔt1£«t2£½(yA£«yB)£«2yP£½£2£«2£½0£¬ 16