两条异面直线的距离也不必要找出公垂线段，只需利用向量的射影性质来解即可。
Two different surface straight lines distance not essential discovers male hangs the line segment, only must solve using the vector projective property then.
交比和无穷远元素是射影几何中的两个重要概念，它们是探讨图形射影性质的主要工具。
Cross ratio and element at infinity are two important concepts with projective geometry and primary tools in considerate projective property of figures.
本文研究了底空间为实射影空间时上协边类纤维丛表示的若干性质。
In this paper we deal with some properties of cobordism classes of fiber bundles over the real projective space.
文中利用射影几何中射线比的特殊性质，解决了透视灭点在图板外的透视图画法。
According to the nature of projective scale, it has solved the problem of drawing a cars perspective when perspective vanishing point is out of the drafting board.
证明：在研究多项式系统的几何性质时，多项式系统应当定义成射影空间中奇点集之余维数至少为2的线场。
This note shows that when studying geometric properties, a polynomial system is defined as a line field on a projective space such that its singular set has co dimension at least 2.
中学生在进行几何体射影时首先要把握几何体的大范围拓扑性质，然后才是物体的局部性质或组成部分。
Middle school students would perceive the global-first topological invariance of the solid figure when they make the projection, and then the local property or components.
中学生在进行几何体射影时首先要把握几何体的大范围拓扑性质，然后才是物体的局部性质或组成部分。
Middle school students would perceive the global-first topological invariance of the solid figure when they make the projection, and then the local property or components.
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