1　本单元重、难点分析重点 :棱柱、棱锥、球的概念和性质 ;直棱柱与正棱锥直观图的画法 ,欧拉公式 .在理解棱柱和棱锥的概念时 ,不能把棱柱想成“有两个面互相平行 ,其余各面都是平行四边形的多面体是棱柱” ,也不能把棱锥想成“有一个面是多边形 ,其余各面都是三角形的多面体 1 The emphasis and difficulty of this unit are: the concept and nature of prisms, pyramids, and spheres; the drawing of direct prisms and right-angled pyramids, the Euler formula. When understanding the concept of prisms and pyramids, one cannot think of prisms as The polyhedrons whose two faces are parallel to each other and whose other faces are parallelograms are prisms, nor can they be thought of as “one face is a polygon, and the other faces are triangular polyhedrons.”