已知sin(π/3+α)=3/5,则COS(5π/6+α)值

已知sin(π/3+α)=3/5,则COS(5π/6+α)值
已知sin(π/3+α)=3/5,则COS(5π/6+α)值

已知sin(π/3+α)=3/5,则COS(5π/6+α)值
COS(5π/6+α)=cos（π/2+π/3+α）=
-sin(π/3+α)=-3/5

cos（5π/6+α）
=cos（π/3+π/2+α）
=cos【（π/3+α）+π/2】
=-sin（π/3+α）
=-3/5

已知sin(π/3+α)=3/5
那么cos[π/2-(π/3+α)]=sin(π/3+α)=3/5
即cos(π/6-α)=3/5
即cos(5π/6+α)=cos[-(5π/6+α)]=cos(-5π/6-α)=-cos[π+(-5π/6-α)]=-cos(π/6-α)=-3/5
如果不懂，请追问，祝学习愉快！cos[π/2-(π/3+α)]=sin(π/3+α...

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已知sin(π/3+α)=3/5
那么cos[π/2-(π/3+α)]=sin(π/3+α)=3/5
即cos(π/6-α)=3/5
即cos(5π/6+α)=cos[-(5π/6+α)]=cos(-5π/6-α)=-cos[π+(-5π/6-α)]=-cos(π/6-α)=-3/5
如果不懂，请追问，祝学习愉快！

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