求祥细解析.
1个回答

2向量a-向量b=2√3cosx--2sinx

=4(√3/2cosx-1/2sinx)

=4sin(π/3-x)=--4sin(x-π/3)

因为x属於[0,π],所以x-π/3属於[---π/3,2π/3]

sin(x-π/3)属於[---√3/2,1],--4sin(x-π/3)属於[-4,2√3]

所以|--4sin(x-π/3) |属於[0,4]

因为m>| 2a -b |恒成立,所以m>| 2a -b |的最大值

所以m>4