天心不仁
幼苗
共回答了1448个问题 举报
cosA = (b*b + c*c - a*a )/ 2*b*c =b/2c+c/2b-a^2/2bc
cosB = (a*a + c*c - b*b )/ 2*a*c =a/2c+c/2a-b^2/2ac
cosC = (b*b + a*a - c*c )/ 2*b*a =b/2a+a/2c-c^2/2ba
cosA+cosB+cosC=(b+c)/2a+(c+a)/2b+(a+b)/2c-[a^3+b^3+c^3]/2abc
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1年前
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