△ABC中∵sin(B+A)=2sin(B+C)∴sinC=2sinA为什么?

来源:学生作业帮助网 编辑:六六作业网 时间:2024/11/27 17:25:21
△ABC中∵sin(B+A)=2sin(B+C)∴sinC=2sinA为什么?△ABC中∵sin(B+A)=2sin(B+C)∴sinC=2sinA为什么?△ABC中∵sin(B+A)=2sin(B+

△ABC中∵sin(B+A)=2sin(B+C)∴sinC=2sinA为什么?
△ABC中∵sin(B+A)=2sin(B+C)∴sinC=2sinA为什么?

△ABC中∵sin(B+A)=2sin(B+C)∴sinC=2sinA为什么?
∵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