sin(a-π/4)=1/3,则cos(π/4+a)等于
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sin(a-π/4)=1/3,则cos(π/4+a)等于
cos(π/4+a)=sin[π/2-(π/4+a)]=sin(π/4-a)=-sin(a-π/4)=-1/3
cos(π/4+a)=1/3
1/3
sin(a-π/4)=1/3,则cos(π/4+a)等于
cos(π/4+a)=sin[π/2-(π/4+a)]=sin(π/4-a)=-sin(a-π/4)=-1/3
cos(π/4+a)=1/3
1/3