(1)
b/SinB=c/SinC=a/SinA
b*SinC=c
b*SinA=a
A=3/4TT-C
SinA=Sin3/4TT*CosC-Cos3/4TTSinC
1/2*(CosC+SinC)2*b2+(SinC)2*b2=2b2
1/2+SinC*CosC+(SinC)2=1
2SinC*CosC-(CosC)2+(SinC)2=0
Tan2C=1
C=TT/8
A=5/8TT
(2)
S=1/2*b2*(CosC)2-1/2*b2*SinC*CosC
S=1
题目完整吗啊？已知a^2+c^=2b^2。，这是不是打错啦啊
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