解çï¼
ï¼1ï¼
å©ç¨æ£å¼¦å®ç:a/sinA=b/sinB=c/sinC
âµ a=bcosC+csinB
â´ sinA=sinBcosC+sinCsinB
âµ sinA=sin[Ï-(B+C)]=sin(B+C)
â´ sinBcosC+cosCsinB=sinBcosC+sinCsinB
â´ cosCsinB=sinCsinB
â´ tanB=1
â´ B=Ï/4
ï¼2ï¼
S=(1/2)acsinB=(â2/4)ac
å©ç¨ä½å¼¦å®ç
4=a²+c²-2ac*cos(Ï/4)
â´ 4=a²+c²-â2acâ¥2ac-â2ac
â´ acâ¤4/(2+â2)=2(2+â2)
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å½a=cæ¶çå·æç«
â´ Sçæ大å¼æ¯(â2/4)*2*(2+â2)=â2+1
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