



 
The simplest way to approach this problem is to lay out a pattern for the tetrahedron: Now take the midpoint of two opposite sides of the pattern  and draw a straight line between them (red above). You probably have the information to figure out the length of this line (look at parallel lines of the same length in this picture). Walter Whiteley  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 