ABCD is a regular tetrahedron , its sides are of equal length . E and F are the midpoints of AB and CD respectively .

I am not sure what a tetrahedron is . Can someone show me the sketch ? Thanks !!

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- Aug 17th 2009, 03:16 AM #1

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- Aug 17th 2009, 03:22 AM #2
Hello,

type tetrahedron in google, or google image

And you'll get this, for example :

http://www.math.wichita.edu/history/...trahedron2.gif

(it's a 3-dimension structure)

- Aug 18th 2009, 03:20 AM #3

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- Aug 18th 2009, 10:34 AM #4