# polygon

• February 1st 2010, 01:53 PM
sri340
polygon
How many diagonals does a regular seven-sided polygon contain?
• February 1st 2010, 08:28 PM
Soroban
Hello, sri340!

Quote:

How many diagonals does a regular seven-sided polygon contain?

Take the 7 vertices, 2 at a time: . $_7C_2 \:=\:\frac{7!}{2!\,5!}$

• February 2nd 2010, 08:19 AM
Opalg
Quote:

Originally Posted by Soroban
Hello, sri340!Take the 7 vertices, 2 at a time: . $_7C_2 \:=\:\frac{7!}{2!\,5!}$

... But if you take a "diagonal" to mean a line connecting two non-adjacent vertices then the answer will be less (14, in fact).