已知园O的半径为R,它的内接三角形△ABC中,2R(sin^2A+sin^2C)=((根号2)a-b)*sinB,求△ABC面积S的最大值
人气:196 ℃ 时间:2019-10-18 03:00:08
解答
a/sinA=b/sinB=c/sinC=2R2R(sin² A-sin² C)=(根号2*a-b)*sinBa^2-c^2=根号ab-b^2a^2+b^2-c^2=根号ab利用余弦,cosC=根号2/2利用基本不等式a=b的时候,S最大a=b代入a^2+b^2-c^2=根号ab2a^2-根号2a^2=c^22-根...
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