TITLE: What is the "Donkey Theorem"?
QUESTION [7 upvotes]: I was watching the Turkish version of Who Wants to Be a Millionaire? and they asked this question: 

What field is the Donkey Case (or I guess it can be translated as Donkey Theorem) related to?

The correct answer was Mathematics. I've never heard of it. What is it?

REPLY [2 votes]: The Donkey Theorem is a humorous name for the theorem that triangles can't be proven congruent through ASS (angle, side, side). SSS, ASA, SAS, and AAS can be used to prove congruency because they are static shapes. There are two possible triangles to be made with angle, side, side congruency as shown by the swinging door. 
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