The mathematician Leonard Euler discovered a relationship (pattern) between the number of faces, edges, and vertices in any polyhedron.

Interactive exercise. Assistance may be required. Click on the image. It will open a new window or tab in your browser.

Based on what you observed in the previous sections, enter the number of faces, vertices, and edges for each polyhedron into the table. When you see a pattern, click the "I See a Pattern" button.

preview image of interactive exercise

Source: Euler's Theorem, Learner.org


The pattern that you observe is Euler's Formula:

V E + F = 2

(V = Vertices, E = Edges, F = Faces)

Example: Given a hexagonal prism, use Euler's Formula to find the number of edges.

Count the total number of sides, include the bases. Check Your Answer

Use the information found in the chart or count the number of vertices. Check Your Answer

Use Euler's Formula to verify the number of edges in the hexagonal prism: V E + F = 2


Interactive exercise. Assistance may be required. Substitute the values for the variables by moving the tiles to create the equation.

Simplify and solve for E. E = Check Your Answer

Example: Given a prism with 18 edges in the base, find the number of vertices and edges.

Click on the blanks to check your answers.