For this you will need four pennies. Arrange the pennies so that the centers of all four are equidistant from each other.

Example:

(1) (2) (3) (4)

This will not work because penny 1 and penny 4 are farther apart than penny 1 and penny 2.

If we take a 3-D pyramid, the centres of the pennies at the base will be equidistant (equilateral triangle).

Also, the penny at the top will also be equidistant from each of the 3 other pennies(each of the sides will form an equilateral triangle).

Posted by Sparsh on 2006-05-03 09:26:27