《数学通报》2 0 0 1年第 1期刊登了黎友源老师的文章《三面角的棱面角的计算公式》(以下简称文 [1 ]) ,该文给出了三面角中棱与面所成的角与三面角间的关系 ,公式应用广泛 ,读后受益非浅 .在阅读过程中发现文 [1 ]中的定理可看作《立体几何》课本Ｐ1 2 2页 第 3题的推广 ,是进 In the 1st issue of the “Mathematical Bulletin”, published in 2001, Li Youyuan’s article “Calculation formula for angles of trihedral angles” (hereinafter abbreviated as [1]) was given. The paper gives the edges and faces of the trihedral angles. The relationship between the angle formed and the trihedral angle, the formula is widely used, after reading the benefit is not shallow. In the reading process found that the theorem in [1] can be regarded as the promotion of the third problem of the “Pseudo Geometry” textbook P1 2 page. Is into