sin(A+B)=2sin(B+C)又知道A+B+C=180,为什么sinC=2sinA
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sin(A+B)=2sin(B+C)又知道A+B+C=180,为什么sinC=2sinA
sin(A+B)=2sin(B+C)又知道A+B+C=180,为什么sinC=2sinA
sin(A+B)=2sin(B+C)又知道A+B+C=180,为什么sinC=2sinA
A+B+C=180
所以A+B=180-C,B+C=108-A
sin(A+B)=2sin(B+C)
sin(180-C)=2sin(180-A)
sinC=2sinA
sin(A+B)=2sin(B+C)又知道A+B+C=180,为什么sinC=2sinA
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