OpenStudy (anonymous):

Mario’s company makes unusually shaped imitation gemstones. One gemstone had 12 faces and 20 edges. How many vertices did the gemstone have? 34 vert. 10 vert. 30 vert 8 vert.

5 years ago
OpenStudy (anonymous):

Have you use Euler's Formula before?

5 years ago
OpenStudy (anonymous):

once or twice but I'm not sure exactly what it is

5 years ago
OpenStudy (anonymous):

But hows that work when I don't have the number of vertices? I put it in as x and solve the equation?

5 years ago
OpenStudy (anonymous):

So for any convex polyhedron, the relationship between the Edges, Vertices, and Faces is given by:\[\bf F+V-E=2\]Substitute for the already given number of faces and number of edges and solve for the number of vertices:\[\bf 12+V-20=2 \implies V=?\]

5 years ago
OpenStudy (anonymous):

Oh, ok! I'll so that right now

5 years ago
OpenStudy (anonymous):

*do

5 years ago
OpenStudy (anonymous):

And you understand what convex means right?

5 years ago
OpenStudy (anonymous):

I got 10 vertices =D Isn't convex smaller then 180? Or is that 360?

5 years ago