化简:cosα+cos(2π/3-α)+cos(2π/3+α)
问题描述：
化简:cosα+cos(2π/3-α)+cos(2π/3+α)
答
cosα+cos(2π/3-α)+cos(2π/3+α)
=cosα+cos(2π/3)cosα+sin(2π/3)sinα+cos(2π/3)cosα-sin(2π/3)sinα
=cosα+2cos(2π/3)cosα
=cosα-cosα
=0
答
原式=cosα+(-1/2)cosα+(√3/2)sinα+(-1/2)cosa-(√3/2)sinα
=0
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