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58问答库 > 在△ABC中，角A，B，C的对边分别为a，b，c，且满足2aCOSC-(2b-c)=0

在△ABC中，角A，B，C的对边分别为a，b，c，且满足2aCOSC-(2b-c)=0

1：求角A2：若sinA=2sinB,且a=根号3，求边b,c

2025-04-06 23:17:06

推荐回答（1个）

回答（1）：

(1)2sinAcosC-(2sinB-sinC)=0
2sinAcosC-(2sin(A+C)-C)=0
2sinAcosC-(2sinAcosC+cosAsinC-sinC)=0
2sinAcosC=2sinAcosC+cosAsinC-sinC
因为sinA>0，cosC>0
所以cosAsinC-sinC=0
cosAsinC=sinC
cosA=sinC÷sinC＝1
所以A＝0°

亲，如果你做过此题，希望，你能和我交流一下，我也是刚刚做的。谢谢

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