cos(θ-pai/4)=sin(pai/2-θ-pai/4)=sin(pai/4-θ)=asin(θ pai/4)=-sin(pai/4-θ)=-a 再百科www.zaibaike.com
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cos(θ-pai/4)=sin(pai/2-θ-pai/4)=sin(pai/4-θ)=asin(θ pai/4)=-sin(pai/4-θ)=-a 再百科www.zaibaike.com