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=âï¼2+36ï¼2Ãâ2Ã6Ãcos135°ï¼
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2ï¼simAçå¼
âµâ C=135°ï¼a=æ ¹å·2ï¼b=6ï¼c=5â2
â´cosâ A=ï¼b²+c²ï¼a²ï¼/2bc
=ï¼36+50ï¼2ï¼/2Ã6Ã5â2
=7â2/10
â´sinA=âï¼1ï¼49/50ï¼
=â2/10
3ï¼ABè¾¹ä¸çé«h
âµb=6ï¼sinA=â2/10
h/b=sinA
â´h=b•sinA
=6Ãâ2/10
=3â2/5
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