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问题: 在三角形ABC中,c(sinA-sinB)+b(sinC-sinA)+a(sinB-sinC)的值是

解答:

c(sinA-sinB)+b(sinC-sinA)+a(sinB-sinC)=
2R[sinc(sinA-sinB)+sinB(sinC-sinA)+sinA(sinB-sinC)]=
2R[sinc(sinA-sinB)+sinB(sinC-sinA)+sinA(sinB-sinC)]=
=0