sinx-1=msinx+msinx=(m+1)/(1-m)-1<=sinx<=1分母不等于0-102/(1-m)>01-m>0m<1(m+1)/(1-m)<=1(m+1)/(1-m)-1<=02m/(1-m)<=02m(1-m)<=0m(m-1)>=0m<=0,m>=1所以m<=0