三角形边角关系的一个不等式及应用５５６０００贵州省黔东南师专吴世锦定理三角形的两边之和不大于第三边与第三边所对角的半角的余割值之积．证明设ΔＡＢＣ的三边长为ａ，ｂ，ｃ．则由正弦定理得根据半角公式，我们便得到与上述定理等价的一个比较原始的结论：下面再用... An inequality of triangular edge relations and its application 556000 The sum of the two sides of the triangle of Wu Shijin’s Theorem in southeast Guizhou Province is not greater than the cosecant of the half angle of the third side and the third side. Prove that the three sides of ΔABC are a, b, c. Then from the sine theorem we get the half-angle formula, we get a more primitive conclusion equivalent to the above theorem: