Question

函数y=cos(x-π/3)+cos(x-2/3π)的最大值

Answer 1

y=(1/2)cosx+(√3/2)sinx+(-1/2)cosx+(√3/2)sinx
=√3sinx
所以，y(max)=√3

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Answer 2

解：
y=cos(x-π/3)+cos(x-2π/3)
y=cos(x-π/3)+cos[x-(π-π/3)]
y=cos(x-π/3)+cos[π-(x-π/3)]
y=cos(x-π/3)-cos(x-π/3)
y=0
ymax=0