摘要
本文旨在利用微分几何的方法，给出球面和伪球面上三角形的余弦定理的一个简便的内蕴证明。
Our goal in this paper is to give some explicit intrinsic proofs of thd cosine theorems of triangles on the sphere and the pseudo-spheres froms the point of view of differential geometry.
关键词
伪球面
球面三角
余弦定理
cosine theorem. pseudo-sphere. spherical trigonometry
