Pyramid 棱锥 2.Getting points on the surface of a pyramid棱锥表面取点 Method Draw an auxiliary line or plane going through the point on the pyramid. 方法： 在棱面上过锥顶作一条包含该点的辅助线或辅助平面。 The projection of pointis also visible when it on visible edge or plane. Distinguish 凡在可见表面及棱线上的点，其投影为可见； 判别 The projection of point is not visible when it on invisible edge or plane. 凡在不可见表面及棱线上的点，其投影则为不可见。 Labeling All invisible points are written in brackets. 标注： 对不可见的点加括号以示区别。 Example4.Draw a regular triangular pyramid and get points on the surface.画正三棱维及表面上各点的三视图。 Example5.Draw a regular pentagonal pyramid and get points on the surface.画正五棱锥及表面上各点的三视图。 请点击鼠标左键显示后面内空
6 2.Getting points on the surface of a pyramid 棱锥表面取点 A K C B P E F Draw an auxiliary line or plane going through the point on the pyramid. 在棱面上过锥顶作一条包含该点的辅助线或辅助平面。 Distinguish 判别: Labeling 标注: All invisible points are written in brackets. 对不可见的点加括号以示区别。 请点击鼠标左键显示后面内容 Example4. Draw a regular triangular pyramid and get points on the surface. 画正三棱锥及表面上各点的三视图。 Example5. Draw a regular pentagonal pyramid and get points on the surface. 画正五棱锥及表面上各点的三视图。 Pyramid 棱锥 The projection of point is also visible when it on visible edge or plane. 凡在可见表面及棱线上的点,其投影为可见； The projection of point is not visible when it on invisible edge or plane. 凡在不可见表面及棱线上的点,其投影则为不可见。 Method 方法:
Exercise. Complete each drawing by adding the missing detail. 补全平面立体及其表面上各点的三投影。 (1)Draw a prism and get points on the surface(2)Draw a pyramid and get points on the surface. 画三棱柱及各点的三投影。 画五棱锥及各点的三投影。 Q (b) b" C 解答 解答 请点击解答显示其内容
7 a" Exercise. Complete each drawing by adding the missing detail. 补全平面立体及其表面上各点的三投影。 （1）Draw a prism and get points on the surface. 画三棱柱及各点的三投影。 c' a' (b') a a" b (c") c b" （2）Draw a pyramid and get points on the surface. 画五棱锥及各点的三投影。 a b c a' b' c" 请点击解答显示其内容 (c') (b")