全日制高中《立体几何》（必修）教材在第８３到８４页的例２中介绍了半径为Ｒ的球的直观图画法（未给证明），由于画图顺序不恰当，并且所画三个大圆直观图（椭圆）没有定量标准，使得学生学习时难以把握其画法，画出的图形往往不很直观，本文参考教材提供一种“八点定位... Full-time high school “three-dimensional geometry” (compulsory) textbook Example 2 on pages 83 to 84 describes the ball of R radius intuitive drawing method (not to prove), because the drawing order is not appropriate, and draw three Great circle circular diagram (ellipse) is not a quantitative standard, making it difficult for students to learn their painting, drawing the graphics are often not very intuitive, this reference textbook provides a "eight o ...