在三角形ABC中内角ABC的对边分别为a,b,c,已知已知(cosA-2cosC)/cosB=(2c-a)/b,(1)求sinC/sinB的值
(cosA-2cosC)/cosB=(2c-a)/b
(cosA-2cosC)/cosB=(2sinC-sinA)/sinB
sinBcosA-2sinBcosC=2sinCcosB-sinAcosB
sinBcosA+sinAcosB=2(sinCcosB+sinBcosC)=2sinA
sinC=2sinA,sinC/sinA=2,
我想问sinBcosA+sinAcosB=sinC吗?