Pyramid question - Princeton

[Guest]

I find it difficult to picture the situation. Can someone give me a hint?

When folded, a region, is like 2 pyramids. How many faces and verteces does the region have?

A. 16
B. 18
C. 20
D. 24
E. 30

[Guest]

The correct wording is as follows:

A region is folded in two such that it resembles 2 pyramids. How many faces and verteces does the region have?

A. 16
B. 18
C. 20
D. 24
E. 30

Can someone provide guidance to this problem.

[Rustic Myth]

the number of verteces will be 6 and the faces will be 10. Adding them up will give us 16.

will have to be visualized.





i hope this helps.

[Guest]

I think the vertices are 5. Thus, answer is 20.

[esledge]

The language in this problem seems a little under-defined to me. According to my dictionary (Random House College Dictionary, 1982 Revised Ed.), pyramids have "a polygonal base with triangular sides that meet at an apex." The accompanying figure shows triangles with square bases, triangular bases, etc. Clearly, the one you chose would affect the number of vertices and faces.

Spatial thinking is one of my strengths, but I'm having a hard time imagining how a region (like a flat piece of paper?) would be folded to create such a shape, without requiring cutting.

My advice: ignore this one.