2asin(C+Ï/6) = b+c
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2sinAsin(C+Ï/6) = sinB+sinC
2sinA{sinCcosÏ/6+cosCsinÏ/6) = sinB+sinC
sinA{â3sinC+cosC) = sinB+sinC
â3sinAsinC+sinAcosC = sinB+sinC
åï¼sinB=sin(A+C) = sinAcosC+cosAsinC
â´ â3sinAsinC+sinAcosC = sinAcosC+cosAsinC +sinC
â´ â3sinAsinC =cosAsinC +sinC
两边åé¤ä»¥sinCå¾ï¼
â3sinA =cosA + 1
â3sinA - cosA = 1
2(sinAcosÏ/6 - cosAsinÏ/6) = 1
sinï¼A-Ï/6) = 1/2
A-Ï/6 â 5Ï/6
â´ A-Ï/6 = Ï/6
â´ A = Ï/3
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