sin(2a-b)-2cos(a+b)sina/sinb=sin(2a-b)-2[sinacosacosb-sinasinasinb]/sinb=sin(2a-b)-sin2acotb+2sin^2(a)=sin(2a-b)-sin2acotb+1-cos2a=sin2acosb-cos2asinb-sin2acotb+1-cos2a=sin2acosb-sin2acotb-cos2asinb-c...