Faces
Vertices, Edges and Faces
A vertex is a corner.
An edge joins one vertex with another.
A face is an individual surface.
Let us look more closely at each of those:
Vertices
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A vertex (plural: vertices) is a point where two or more straight lines meet. It is a Corner. This tetrahedron has 4 vertices. |
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And this pentagon has 5 vertices |
Edges
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An edge is a line segment that joins two vertices. This tetrahedron has 6 edges. And this pentagon has 5 edges |
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It can also be the boundary of a shape. Such as the circumference of a circle. |
Faces
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A face is any of the individual surfaces of a solid object. This tetrahedron has 4 faces (there is one face you can't see) |
Euler's Formula
For many solid shapes the
- Number of Faces
- plus the Number of Vertices
- minus the Number of Edges
always equals 2
This can be written: F + V - E = 2
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Try it on the cube: A cube has 6 Faces, 8 Vertices, and 12 Edges, so: 6 + 8 - 12 = 2 |
