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Subject: "diagonals"     Previous Topic | Next Topic
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Conferences The CTK Exchange Middle school Topic #41
Reading Topic #41
Mike Ranium (Guest)
guest
 Apr-30-01, 08:54 AM (EST)
 
"diagonals"
 
   What is a formula for the number of diagonals in an n-sided convex polygon, where n * 3 (a greater than sign plus a line under it like an equal sign)?


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alexb
Charter Member
672 posts		 Aug-03-01, 03:08 PM (EST)
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1. "RE: diagonals"
In response to message #0
 
   n·(n - 3)/2.

Each vertex can be linked by a diagonal to n - 3 others, excluding it'self and the two neighboring vertices to which it is linked by a side. Each diagonal is counted twice as it has two ends.


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