How many diagonals does a regular seven-sided polygon contain?
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Hello, sri340! How many diagonals does a regular seven-sided polygon contain? Take the 7 vertices, 2 at a time: . $\displaystyle _7C_2 \:=\:\frac{7!}{2!\,5!}$
Originally Posted by Soroban Hello, sri340!Take the 7 vertices, 2 at a time: . $\displaystyle _7C_2 \:=\:\frac{7!}{2!\,5!}$ ... But if you take a "diagonal" to mean a line connecting two non-adjacent vertices then the answer will be less (14, in fact).
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