在基本几何体的投影学习过程中，同学们了解到，基本几何体是表面由若干个面构成的，表面均由平面构成的形体称为平面立体，表面由曲面或平面与曲面构成的形体称为曲面立体。由于曲面立体的形成特点，它又被称为回转体，常见的回转体有圆柱、圆锥、圆球等。空间基本几何体作图 In the basic geometry of the projection learning process, students learned that the basic geometry is the surface composed of a number of surfaces, the surface is composed of flat body is called the plane three-dimensional, the surface by the surface or surface and the surface form is called the surface Three-dimensional. Due to the formation of three-dimensional surface features, it is also known as the rotary body, a common rotating body cylinder, cone, sphere and so on. Space basic geometry drawing