For this you will need four pennies. Arrange the pennies so that the centers of all four are equidistant from each other.
(1) (2) (3) (4)
This will not work because penny 1 and penny 4 are farther apart than penny 1 and penny 2.
The problem doesn't state that the four pennies need to remain on the same surface or in the same plane, so I think I'll form an equilateral triangle with three them on the table and hold the fourth up above to form an equilateral pyramid.
Posted by Jyqm
on 2006-05-01 09:23:48