(1)Çótan CµÄÖµ;
(2)Èô¡÷ABCµÄÃæ»ýΪ3,ÇóbµÄÖµ.
25.(2015¡¤É½¶«¡¤ÀíT16)Éèf(x)=sin xcos x-cos2
.
(1)Çóf(x)µÄµ¥µ÷Çø¼ä;
(2)ÔÚÈñ½Ç¡÷ABCÖÐ,½ÇA,B,CµÄ¶Ô±ß·Ö±ðΪa,b,c.Èôf
=0,a=1,Çó¡÷ABCÃæ»ýµÄ×î´óÖµ.
26.(2015¡¤ÉÂÎ÷¡¤ÀíT17)¡÷ABCµÄÄÚ½ÇA,B,CËù¶ÔµÄ±ß·Ö±ðΪa,b,c,ÏòÁ¿m=(a,ÐÐ. (1)ÇóA; (2)Èôa=
,b=2,Çó¡÷ABCµÄÃæ»ý.
b)Óën=(cosA,sinB)ƽ
27.(2015¡¤½ËÕ¡¤ÀíT15)ÔÚ¡÷ABCÖÐ,ÒÑÖªAB=2,AC=3,A=60¡ã. (1)ÇóBCµÄ³¤; (2)Çósin 2CµÄÖµ.
28.(2015¡¤Õ㽡¤ÎÄT16)ÔÚ¡÷ABCÖÐ,ÄÚ½ÇA,B,CËù¶ÔµÄ±ß·Ö±ðΪa,b,c.ÒÑÖªtan
=2.
(1)ÇóµÄÖµ;
(2)ÈôB=,a=3,Çó¡÷ABCµÄÃæ»ý.
29.(2015¡¤Ìì½ò¡¤ÎÄT16)ÔÚ¡÷ABCÖÐ,ÄÚ½ÇA,B,CËù¶ÔµÄ±ß·Ö±ðΪa,b,c.ÒÑÖª¡÷ABCµÄÃæ»ýΪ3
,b-c=2,cos A=-.
(1)ÇóaºÍsin CµÄÖµ; (2)Çócos
µÄÖµ.
30.(2015¡¤È«¹ú2¡¤ÎÄT17)¡÷ABCÖÐ,DÊÇBCÉϵĵã,ADƽ·Ö¡ÏBAC,BD=2DC.
(1)Çó;
(2)Èô¡ÏBAC=60¡ã,Çó¡ÏB.
31.(2015¡¤°²»Õ¡¤ÀíT16)ÔÚ¡÷ABCÖÐ,¡ÏA=,AB=6,AC=3
,µãDÔÚBC±ßÉÏ,AD=BD,ÇóADµÄ³¤.
32.(2014¡¤È«¹ú2¡¤ÎÄT17)ËıßÐÎABCDµÄÄÚ½ÇAÓëC»¥²¹,AB=1,BC=3,CD=DA=2. (1)Çó½ÇCºÍBD;
(2)ÇóËıßÐÎABCDµÄÃæ»ý.
33.(2014¡¤Õ㽡¤ÀíT18)ÔÚ¡÷ABCÖÐ,ÄÚ½ÇA,B,CËù¶ÔµÄ±ß·Ö±ðΪa,b,c.ÒÑÖªa¡Ùb,c=Acos A-sin Bcos B.
,cosA-cosB=
2
2
sin
(1)Çó½ÇCµÄ´óС;
(2)Èôsin A=,Çó¡÷ABCµÄÃæ»ý.
34.(2014¡¤ÁÉÄþ¡¤ÀíT17)ÔÚ¡÷ABCÖÐ,ÄÚ½ÇA,B,CµÄ¶Ô±ß ·Ö±ðΪa,b,c,ÇÒa>c.ÒÑÖª
=2,cos B=,b=3.Çó:
(1)aºÍcµÄÖµ; (2)cos(B-C)µÄÖµ.
35.(2014¡¤Ìì½ò¡¤ÎÄT16)ÔÚ¡÷ABCÖÐ,ÄÚ½ÇA,B,CËù¶ÔµÄ±ß·Ö±ðΪa,b,c.ÒÑÖªa-c=b,sin B=
sin C.
(1)Çócos AµÄÖµ;
(2)ÇócosµÄÖµ.
36.(2014¡¤±±¾©¡¤ÀíT15)Èçͼ,ÔÚ¡÷ABCÖÐ,¡ÏB=,AB=8,µãDÔÚBC±ßÉÏ,ÇÒCD=2,cos ¡ÏADC=.
(1)Çósin ¡ÏBAD; (2)ÇóBD,ACµÄ³¤.
37.(2014¡¤ºþÄÏ¡¤ÀíT18)Èçͼ,ÔÚƽÃæËıßÐÎABCDÖÐ,AD=1,CD=2,AC=(1)Çócos ¡ÏCADµÄÖµ; (2)Èôcos¡ÏBAD=-,sin ¡ÏCBA=
,ÇóBCµÄ³¤.
.
38.(2014¡¤ºþÄÏ¡¤ÎÄT19)Èçͼ,ÔÚƽÃæËıßÐÎABCDÖÐ,DA¡ÍAB,DE=1,EC=,EA=2,¡ÏADC=,¡ÏBEC=.
(1)Çósin ¡ÏCEDµÄÖµ; (2)ÇóBEµÄ³¤.
39.(2013¡¤È«¹ú2¡¤ÀíT17)¡÷ABCµÄÄÚ½ÇA,B,CµÄ¶Ô±ß·Ö±ðΪa,b,c,ÒÑÖªa=bcosC+csinB. (1)ÇóB;
(2)Èôb=2,Çó¡÷ABCÃæ»ýµÄ×î´óÖµ.
40.(2013¡¤È«¹ú1¡¤ÀíT17)Èçͼ,ÔÚ¡÷ABCÖÐ,¡ÏABC=90¡ã,AB=(1)ÈôPB=,ÇóPA;
,BC=1,PΪ¡÷ABCÄÚÒ»µã,¡ÏBPC=90¡ã.
(2)Èô¡ÏAPB=150¡ã,Çótan¡ÏPBA.
41.(2012¡¤È«¹ú¡¤ÎÄT 7)ÒÑÖªa,b,c·Ö±ðΪ¡÷ABCÈý¸öÄÚ½ÇA,B,CµÄ¶Ô±ß,c=(1)ÇóA;
(2)Èôa=2,¡÷ABCµÄÃæ»ýΪ
,Çób,c.
asin C-ccosA.
42.(2012¡¤È«¹ú¡¤ÀíT17)ÒÑÖªa,b,c·Ö±ðΪ¡÷ABCÈý¸öÄÚ½ÇA,B,CµÄ¶Ô±ß,acos C+(1)ÇóA;
(2)Èôa=2,¡÷ABCµÄÃæ»ýΪ
,Çób,c.
asin C-b-c=0.
43.(2010¡¤ÉÂÎ÷¡¤ÀíT17)Èçͼ,A,BÊǺ£ÃæÉÏλÓÚ¶«Î÷·½ÏòÏà¾à5(3+)º£ÀïµÄÁ½¸ö¹Û²âµã.ÏÖλÓÚAµã±±
º£Àï
Æ«¶«45¡ã,Bµã±±Æ«Î÷60¡ãµÄDµãÓÐÒ»ËÒÂÖ´¬·¢³öÇó¾ÈÐźÅ,λÓÚBµãÄÏÆ«Î÷60¡ãÇÒÓëBµãÏà¾à20µÄCµãµÄ¾ÈÔ®´¬Á¢¼´Ç°ÍùÓª¾È,Æ亽ÐÐËÙ¶ÈΪ30º£Àï/ʱ,¸Ã¾ÈÔ®´¬µ½´ïDµãÐèÒª¶à³¤Ê±¼ä?