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

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.

There is no graph to look at on here, but i shall explain them to you. a line graph is just in its title it’s a graph with a line running through the dots to show an increase or decrease. a bar graph is used to show how much or how little something is so a comparison. a scatter plot is used to graph points to tell the data. and i don’t know what a histogram is.