You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: MATHEMATICS 
Clue: Term for the side of a right triangle that is opposite the 90° angle
hypoteneuse

Category: PLAYWRIGHTS 
Clue: In 1979 this author of "Streamers" married Jill Clayburgh
david rabe

Category: HOW LOW CAN YOU GO? 
Clue: "I went fishing just for the halibut" is one of these, which have been termed "the lowest form of wit"

a pun