若cos(α-π/6)+sinα=4√3/5,则s

1个回答

展开cos(α-π/6)+sinα
=√3/2cosα+1/2sinα+sinα=√3/2cosα+3/2sinα=4√3/5
两边同除√3,得1/2cosα+√3/2sinα=4/5,
合并,sin（α+π/6)=4/5
看要求的式子是sin(α+7π/6）=-sin（α+π/6)=-4/5.

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