Find a two dimensional shape so that four congruent copies can be arranged on a plane so that each copy touches all three other copies along some segment of positive length.

Show that there is a three dimensional shape so that any finite number of copies can be arranged in space so that each copy touches all the other copies along some region of positive area.

Note 1: You may use the reflection of a shape.
Note 2: Touching at only a corner is NOT sufficient.

3D question proposed by Leming.

Draw an equilateral triangle. Make each line representing a side 10 cm long and 1 cm wide.

Make a perpendicular cut to each side at the mid-point. 

There should be three identical shapes that look like "V".

Make a fourth "V", identical to the first three.  Set it in the middle of the triangle made by the first three and position it so it touches the other three.

 

 

 

 

 

 

Posted by Leming on 2008-01-23 17:32:44