elfc
幼苗
共回答了21个问题采纳率:95.2% 举报
由余弦定理可知,a^2 = b^2+ c^2 - 2·b·c·cosA b^2 = a^2 + c^2 - 2·a·c·cosB c^2 = a^2 + b^2 - 2·a·b·cosC.化简可得 cosC = (a^2 + b^2 - c^2) / (2·a·b) cosB = (a^2 + c^2 -b^2) / (2·a·c) cosA = (c^2 + b^2 - a^2) / (2·b·c).由反三角函数可求得各角ABC值
1年前
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