Notes
Euler’s Formula
\(F+V-E=2\)
\(F=\)Faces
\(V=\)Vertices
\(E=\)Edges
Practice Problems
\(\textbf{1)}\) How many faces, vertices, & edges does the following figure have?

There are \( 6 \) faces.
There are \( 8 \) vertices.
There are \( 12 \) edges.
\(\textbf{2)}\) How many faces, vertices, & edges does the following figure have?

There are \( 5 \) faces.
There are \( 6 \) vertices.
There are \( 9 \) edges.
\(\textbf{3)}\) A tetrahedron has 4 faces and 4 vertices. How many edges does it have?
There are \( 6 \) edges.
\(\,\,\,\,\,\,F+V-E=2\)
\(\,\,\,\,\,\,(4)+(4)-E=2\)
\(\,\,\,\,\,\,8-E=2\)
\(\,\,\,\,\,\,-E=-6\)
\(\,\,\,\,\,\,E=6\)
\(\,\,\,\,\,\,\)There are \( 6 \) edges.
\(\textbf{4)}\) A octahedron has 8 faces and 12 edges. How many vertices does it have?
There are \( 6 \) vertices.
\(\,\,\,\,\,\,F+V-E=2\)
\(\,\,\,\,\,\,(8)+V-(12)=2\)
\(\,\,\,\,\,\,-4+V=2\)
\(\,\,\,\,\,\,V=6\)
\(\,\,\,\,\,\,\)There are \( 6 \) vertices.
\(\textbf{5)}\) A dodecahedron has 20 vertices and 30 edges. How many faces does it have?
There are \( 12 \) faces.
\(\,\,\,\,\,\,F+V-E=2\)
\(\,\,\,\,\,\,F+(20)-(30)=2\)
\(\,\,\,\,\,\,F-10=2\)
\(\,\,\,\,\,\,F=12\)
\(\,\,\,\,\,\,\)There are \( 12 \) faces.
\(\textbf{6)}\) An icosahedron has 20 faces and 12 vertices. How many edges does it have?
There are \( 30 \) edges.
\(\,\,\,\,\,\,F+V-E=2\)
\(\,\,\,\,\,\,(20)+(12)-E=2\)
\(\,\,\,\,\,\,32-E=2\)
\(\,\,\,\,\,\,-E=-30\)
\(\,\,\,\,\,\,E=30\)
\(\,\,\,\,\,\,\)There are \( 30 \) edges.
See Related Pages\(\)
