∵B+A+C=π
sin(B+A)=2sin(B+C)
∴sin(B+A)=sin(π-C)=sinC
2sin(B+C)=2sin(π-A)=2sinA
∴sinC=2sinA
△ABC中∵sin(B+A)=2sin(B+C)∴sinC=2sinA為什么?
△ABC中∵sin(B+A)=2sin(B+C)∴sinC=2sinA為什么?
數(shù)學(xué)人氣：268 ℃時間：2020-05-17 20:58:07
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