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来源：学生作业帮助网 编辑：作业帮 时间：2024/11/27 04:41:19
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已知0
已知0<α<45°,sin(45°-α)=1/3,则cos(45°+α)=?
已知0
cos(45°＋a)
=sin[90°－(45°＋a)]
=sin(45°－a)
=1/3
sin(45°-α)=1/3
那么cos(45°+α)=cos[90°-(45°-α)]=sin(45°-α)=1/3
cos(45°+α)=sin（90°-（45°＋α））=sin(45°-α)=1/3