在机器的零件、管道中的接头中，经常遇到两个立体表面相交的情况，正确地画出其相贯线，可清楚地区分立体表面的界线，并有助于读图。工程上特别是对于板金制件，更需要根据相贯线做出其展开图进行放样下料，因此，准确地求解相贯线的投影，尤其是极位点的投影，对于工程... In the parts of the machine, joints in pipes, it is common to encounter the intersection of two solid surfaces, correctly plotting their intersection lines, clearly distinguishing the boundaries of the solid surface and helping to read the drawings. Engineering, especially for sheet metal parts, but also need to make its expansion plans according to the intersection of the line out of stock, therefore, accurately solve the projection of the intersecting line, especially the projection of the polar site, for the project ...