SOLUTION: Is it possible to have a polygon with number of diagonals twice the number of its sides?

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Question 1120600: Is it possible to have a polygon with number of diagonals twice the number of its sides?
Answer by greenestamps(13203) About Me  (Show Source):
You can put this solution on YOUR website!


This seems like a problem you could answer rather easily if you wanted to think a little bit....

In case you aren't familiar with it, the formula for the number of diagonals in a polygon with n sides is (n(n-3))/2. (n-3 diagonals from each of the n vertices; each one gets counted twice, once from each end.)

Given that formula, you could simply try different small values of n and see if you can find one that satisfies the condition.

Or assuming you know a little algebra, you can solve the equation that says the number of diagonals is twice the number of sides:

%28n%28n-3%29%2F2%29+=+2n
....

(multiply both sides by 2 and divide by n....)