已知sin(α-π/4)=1/3,则cos(π/4+α)的值为——
人气:476 ℃ 时间:2020-01-23 13:56:09
解答
sin(α-π/4)=1/3
cos(π/4+α) = sin{π/2-(π/4+α)} = sin{π/4-α} = sin{-(α-π/4)} = -sin(α-π/4)=-1/3
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