sin(a-b)=sin(a)cos(b)-sin(b)cos(a);故sin(a-b)+3/5=-2sin(b)cos(a) sin(a)cos(b)-sin(b)cos(a)+3/5=-2sin(b)cos(a); 将右面的移到左边,得 sin(a)cos(b)-sin(b)cos(a)+3/5+2sin(b)cos(a)=0；化简的sin(a)cos(b)+s...