Posted by ggift on .
If a polyhedron has 13 vertices and 21 faces, how many edges does it have? I can't figure this one out.

GEOMETRY 
MathMate,
Use Euler's formula which says that
V+F=E+2
where
V=vertices
F=faces
E=edges
For example, a cube has 8 vertices, 6 faces and 12 edges, so
8+6=12+2 
GEOMETRY 
ggift,
ok thanks!!

GEOMETRY :) 
MathMate,
You're welcome!

GEOMETRY 
qamar,
For a given polyhedron, there are 24 vertices and 32 faces. How many edges does the polyhedron have? [Hint: V + F = E + 2.]