SOLUTION: a polygon has n sides has n diagonals. What is n?

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Question 1056652: a polygon has n sides has n diagonals. What is n?
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.
%28n%2A%28n-3%29%29%2F2 = n   ====>

n%5E2-3n = 2n,

n%5E2 = 5n  ====>

n = 5.

Answer. Pentagon.