Through proof and using geometric methods, this paper presents some conclusions about orthographies, projective characteristics and position in space of oblique line with equal dip angles to the planes of projection.
运用几何学，通过证明对一般位置等倾直线投影图形、投影特性及空间各种各样的等倾直线位置进行推导、归纳，从中总结出一般规律，最后给出结论。