两个三角恒等式及Euler公式的推广

Two trigonometric identities and Euler formula' proof

第一部分给出两个三角恒等式及其证明,然后应用它给出了微分几何中平均曲率的一个重要结果及其证明;第二部分对E3中的一些概念在En中进行了平行推广,再将E3中的Eu ler公式κn(θ)=κ1cos2θ+κ2sin2θ推广到En中,得到En中关于平均曲率积分与法曲率积分相关的关系式。

In the first part of this thesis we give two trigonometric ldenuues ana prow them.Then we apply them to give an important result about mean curvature and its proof in the differential geometry. In the second part, we extend some concepts and Euler formula Kn（θ） = K1cos^2θ ＋ K2sin^2θin E3 to in En and obtain a relative formula about the mean curvature integral and the normal curvature in En.