Question

In drawing, the outer boundaries of two-dimensional forms are defined by ________, while the outer boundaries perceived among three-dimensional forms are defined by ________.

Answer 1

The answer to the first unknown in the problem is "OUTLINE" while the second unknown in the problems is referring to "CONTOUR LINES". In drawing or other drawing related arts, the other boundaries of the two-dimensional forms are defined by the so-called "OUTLINE" while the outer boundaries perceived among the three-dimensional forms are described and defined by CONTOUR LINES.