因C=π/3,所以 A+B=2π/3,A=2π/3-BsinB=2SinA=2Sin(2π/3-B)=2(sin(2π/3)cosB-cos(2π/3)sinB)=根号3*cosB+sinB根号3*cosB=0,cosB=0,得B=π/2,从而A=π/6,知三角形ABC为直角三角形.由正弦定理c/sinC=a/sinA=b/sinb...