ËùÒÔAC=8=6.¹ÊÑ¡D.
13.150 ÔÚRt¡÷ABCÖÐ,¡ÏCAB=45¡ã,BC=100 m,ËùÒÔAC=100 m.
ÔÚ¡÷AMCÖÐ,¡ÏMAC=75¡ã,¡ÏMCA=60¡ã,´Ó¶ø¡ÏAMC=45¡ã,ÓÉÕýÏÒ¶¨Àí,µÃ´ËAM=100
m.
m,¡ÏMAN=60¡ã,ÓÉ
,Òò
ÔÚRt¡÷MNAÖÐ,AM=100µÃMN=100
=sin 60¡ã,
=150(m).
=2R=
,
14.½â (1)ÓÉÕýÏÒ¶¨Àí¿ÉµÃ
=2R=(2)ÓÉÕýÏÒ¶¨Àí¿ÉµÃ, ¡àc=2.
22222
ÓÉÓàÏÒ¶¨Àí¿ÉµÃ2=a+b-2abcos 60¡ã,»¯Îªa+b-ab=4. ÓÖa+b=ab,
¡à(a+b)2-3ab=a2b2-3ab=4,½âµÃab=4.
¡à¡÷ABCµÄÃæ»ýS=15.C
absin C=4¡Ásin 60¡ã=
Èçͼ,È¡BCµÄÖеãD,Á¬½ÓPD,ÔòPD=4.ÉèBD=x,ÔòPB=PC=µÃ,(2x)=(2,C2
ÓÉÓàÏÒ¶¨Àí¿É
)+()-2(
2
)cos¡ÏBPC,½âµÃx=3(¸ºÖµÉáÈ¥).ÔòB-,-2
,-2,¹ÊBP,CPµÄÖе㶼ÊÇf(x)ͼÏóµÄ¶Ô³ÆÖÐÐÄ.
sin ¦Øx-2sin
2
16.½â (1)f(x)=+m=sin ¦Øx-1+cos ¦Øx+m
=2sin
ÒÀÌâÒâ
-1+m. =3¦Ð,¦Ø=,
ËùÒÔf(x)=2sin
µ±x¡Ê[0,¦Ð]ʱ,
ËùÒÔf(x)µÄ×îСֵΪm. ÒÀÌâÒâ,m=0. ËùÒÔf(x)=2sin(2)ÒòΪf(C)=2sin¶ø
,
-1+m.
sin
1,
-1.
-1=1,ËùÒÔsin
=1.
ËùÒÔ½âµÃC=
2
ÔÚRt¡÷ABCÖÐ,ÒòΪA+B=,2sinB=cos B+cos(A-C),
2