Finding a formula for a sum
- To: mathgroup at smc.vnet.net
- Subject: [mg35104] Finding a formula for a sum
- From: Matthias.Bode at oppenheim.de
- Date: Tue, 25 Jun 2002 03:39:48 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Dear Colleagues, when trying to find the number of diagonals in a convex polygon (all corners on the perimeter of a circle) with n corners I came across that sum: +(n-3) ; up to here = diagonals in a triangle. +(n-3) ; up to here = diagonals in a quadrangle. +(n-4) ; up to here = diagonals in a pentagon. +(n-5) ; up to here = diagonals in a hexagon. +(n-6) ; up to here = diagonals in a heptagon. and so on. I found the general formula (n*n -3*n)/2 with pencil and paper. How could I coax MATHEMATICA into helping me to find the generalization in this case - and of course for more difficult ones as well? Best regards, Matthias Bode Sal. Oppenheim jr. & Cie. KGaA Koenigsberger Strasse 29 D-60487 Frankfurt am Main GERMANY Tel.: +49(0)69 71 34 53 80 Mobile: +49(0)172 6 74 95 77 Fax: +49(0)69 71 34 95 380 E-mail: matthias.bode at oppenheim.de Internet: http://www.oppenheim.de