a=(2,-1)
b=(sinx+cosx,1+sin2x)
f(x)=m(2sinx+2cosx-1-sin2x+√3sin2x)
=m(2(sinx+cosx)+2(√3-1)sinxcosx-1)
sinx+cosx=t=2^1/2sin(x+pai/4)
(3^1/2+1)/2<=t<=2^1/2
sinxcosx=(t^2-1)/2
m(2t+(√3-1)(t^2-1)-1)
m>0
t=2^1/2,m(2*2^1/2+(3^1/2-1)-1)=1
m=1/(2*2^1/2+3^1/2-2)
m<0
t=2^1/2,f(t)=3^1/2/2
m=3/(4*6^1/2+6-4*3^1/2)>0
舍
m=1/(2*2^1/2+3^1/2-2)
=m(