3sinA5sinB的知识精选

设△ABC的内角A,B,C所对边的长分别为a,b,c,若b+c=2a,3sinA=5sinB,则角C=(A)π...
问题详情:设△ABC的内角A,B,C所对边的长分别为a,b,c,若b+c=2a,3sinA=5sinB,则角C=(A)π/3                                 (B)2π/3(C)3π/4                     ...
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