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最佳答案:sina=(√2+√6)/4=sinπ/6cosπ/4+cosπ/6sinπ/4=sin(π/6+π/4)=sin5π/12 ,a=5π/12a+b=5π/12
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最佳答案:答案:A根据正弦定理可得,CB/sin∠BAC=BA/sin∠ACB,即d/sin∠BAC=BA/sinθ所以,BA=dsinθ/sin∠BAC,由已知及图可知