1.定义 从一点出发并且不在同一平面内的几条射线,以及每两条相邻射线间的平面部分组成的空间图形叫做多面角,这些射线叫做多面角的棱,这些射线的公共点叫做多面角的顶点,相邻两条棱之间的平面部分叫做多面角的面,每个面内由两条棱组成的角叫做多面角的面角,每相邻的两个面构成的二面角叫做多面角的 1. Define a few rays that start from a point and are not in the same plane, and the spatial pattern formed by the plane part between every two adjacent rays is called polyhedral angle. These rays are called polygon angles. The common point of these rays is called multifaceted. The vertex of the corner, the plane between the adjacent two edges is called polyhedral face, the angle formed by two edges in each face is called the face angle of the polyhedral angle, and the dihedral angle formed by each adjacent two faces. Polyhedral