
解一下数学变式题,谢啦
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cos(a-π/6)+sina
=cosacosπ/6+sinasinπ/6+sina
=√3/2cosa+1/2sina+sina
=√3/2cosa+3/2sina
=√3 (1/2cosa+√3/2sina)
=√3 (sinπ/6cosa+cosπ/6sina)
=√3sin(a+π/6)
=4√3/5
所以
sin(a+π/6)=4/5
=cosacosπ/6+sinasinπ/6+sina
=√3/2cosa+1/2sina+sina
=√3/2cosa+3/2sina
=√3 (1/2cosa+√3/2sina)
=√3 (sinπ/6cosa+cosπ/6sina)
=√3sin(a+π/6)
=4√3/5
所以
sin(a+π/6)=4/5
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