YE Xiao _ qin. Discussion about Some Questions of the Profile Line[J]. Journal of Civil and Environmental Engineering, 1999, 21(4): 102-105. DOI: 10.11835/j.issn.1674-4764.1999.04.022.
This paper discusses some questions about the profile line of space geometry
such as the judgement of the parallelism of the two profile lines with the same directions and the visibility about the skew lines and the reappeared points of profile lines
which make the solution of some questions in space geometry more easy than those commonly used.