What a prism has 21 edges?

Answer 1

A prism with 21 edges would have a polygonal base that is a decagon (10 sides). Since a prism consists of two parallel bases and vertical edges connecting corresponding vertices, the total number of edges can be calculated as the sum of the edges of the two bases (10 + 10) and the number of vertical edges (10), resulting in 30 edges. However, since the question specifies 21 edges, this indicates an error, as no standard prism can have 21 edges. A correct example would be a prism with 6 edges (triangular base) or 12 edges (hexagonal base).