Explain how the expansion of the United States intensified sectionalism

Southern states wanted new slave territories, while the north wanted to contain the spread of slavery. while western expansion contributed to growing sectional tensions between the north and south from 1800-1820

The question is asking to state the polygon that connects with the base of polyhedron, base on my research and further analysis, I would say that the answer would be a parallelograms formed by segments (lateral edges) connecting the corresponding vertices of the bases. I hope this would help