1. Sep 25, 2005 #1

   fork

   

   Find the number of diagonals that can be drawn in an n-side polygon.
   
   The answer is n(n-3)/2.
   
   I don't know how to do that.

    

   fork, Sep 25, 2005
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3. Sep 25, 2005 #2

   Tide

   

   Science Advisor

   Homework Helper

   Set up a recursion for the number of diagonals in an n-gon: [itex]D_{n+1} = D_n + n - 2[/itex].

    

   Tide, Sep 25, 2005
4. Sep 25, 2005 #3

   fork

   

   I don't understand how can I set up
   [itex]D_{n+1} = D_n + n - 2[/itex].

    

   fork, Sep 25, 2005
5. Sep 25, 2005 #4

   HallsofIvy

   

   Staff Emeritus

   Science Advisor

   How many diagonals can be drawn from 1 vertex? If you multiply that by the number of vertices you will get the wrong answer! Do you see why? How can you fix it?

    

   HallsofIvy, Sep 25, 2005

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