作业帮已知sin(30+α)=1/3,则cos(60-α)=?
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已知sin(30+α)=1/3,则cos(60-α)=?
已知sin(30+α)=1/3,则cos(60-α)=?
已知sin(30+α)=1/3,则cos(60-α)=?
30+α+60-α=90
cos(60-α)=cos[90-(30+α)]=sin(30+α)=1/3
cos(60-α)
=cos[90-(30+a)]
=sin(30+a)=1/3
1/3
cos(60-α)=cos(90-30-α)=cos[90-(30+α)]=sin(30+α)=1/3
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