The Magic Dice Cup

http://en.wikipedia.org/wiki/File:The_Magic_Dice_Cup_tangram_paradox.svg
Image: Wikimedia Commons

A tangram paradox from Sam Loyd’s Eighth Book of Tan (1903). Each of these cups was composed using the same seven geometric shapes. But the first cup is whole, and the others contain vacancies of different sizes.

“Of course it is a fallacy, a paradox, or an optical illusion, for you will say the feat is impossible!” But how is it done?