Difference between revisions of "Euler Characteristic"

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===Tetrahedron===
 
===Tetrahedron===
 
   
 
   
[[Image:Tetrahedron-labeled.svg|500px]]
+
[[Image:Tetrahedron-labeled.svg|400px]]
  
 
How many vertices ("corners") V do you see? _______
 
How many vertices ("corners") V do you see? _______
Line 21: Line 21:
  
 
Did the answer come out to 2?  ______
 
Did the answer come out to 2?  ______
 
  
 
===Octahedron===
 
===Octahedron===

Revision as of 11:44, 6 May 2009

K-12: Materials at high school level.



In 1750, the Swiss mathematician Leonhard Euler discovered a remarkable formula involving the number of faces F, edges E, and vertices V of a polyhedron:

He found that V - E + F = 2

Let's check this formula on some of the shapes below.

Tetrahedron

Tetrahedron-labeled.svg

How many vertices ("corners") V do you see? _______

How may edges E do you see? ______

How many faces ("sides") F do you see? ______

Now find V - E + F = ___ - ___ + ___ =

Did the answer come out to 2? ______

Octahedron

Octahedron-labeled.svg

How many vertices ("corners") V do you see? _______

How may edges E do you see? ______

How many faces ("sides") F do you see? This may be easier to count in the figure on the right. ______

Now find V - E + F = ___ - ___ + ___ =

Did the answer come out to 2? ______