在三角形ABC中,内角A,B,C的对边边长分别是a,b,c,已知a^2+c^=2b^2.
2个回答

(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

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