2 2 2BC A CA B AB C4 4 4  B C; ; . 2 2 22 2 2BC A CA B AB C  C...

Câu 1:

2

2

2

bc a ca b ab c

4 4 4

  

B C

; ; .

 

2 2 2

bc a ca b ab c

  

Cho A =

CMR: Nếu a+b+c = 0 thì:

a, ABC = 1

b, A + B + C = 3