1), whether or not the projection of ultra-left point on intersecting line is finded out, it will affect the precise of intersecting line directly, However, there is no paper that presents and discusses the method to fed the ultra-left point now.
运用数学解析法，给出了相贯线正面投影的数学表达式，从而确定了最左点的坐标，并由此获得了用几何作图作出该点的简捷方法。