`asinx+bcosx`
`sinx-sqrt3cosx=(4m-6)/(4-m)`
`2(1/2sinx-sqrt3/2cosx)=(4m-6)/(4-m)`
`2(cospi/3*sinx-sinpi/3*cosx)=(4m-6)/(4-m)`
`2(sin(x-pi/3))=(4m-6)/(4-m)`
`sin(x-pi/3)=(2m-3)/(4-m)`
`-1<=sin(x-pi/3)<=1`<br>
`-1<=(2m-3)/(4-m)<=1`<br>
`(2m-3)/(4-m)+1>=0`
`(2m-3+4-m)/(4-m)>=0`
`(m+1)/(4-m)>=0`
`m in[-1,4)`
`(2m-3)/(4-m)-1<=0`<br>
`(2m-3-4+m)/(4-m)<=0`<br>
`(3m-7)/(4-m)<=0`<br>
`m in(-oo,7/3]uu(4,oo)`
`m in[-1,7/3]`
`m=-1,0,1,2`.