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问题: 函数y=cosx+cos(x+π/3)的最大值为_

函数y=cosx+cos(x+π/3)的最大值为__

解答:

先化简
y=cosx+cos(x+π/3)
=cosx+cosx*cosπ/3-sinx*sinπ/3
=cosx+(1/2)cosx-(√3/2)sinx
=(3/2)cosx-(√3/2)sinx
=√3*[(√3/2)cosx-(1/2)sinx]
=√3*(sinπ/3*cosx-cosπ/3*sinx)
=√3*sin(π/3-x)
很明显,最大值为√3