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2013 AMC 10A Problems/Problem 25

Revision as of 00:10, 7 February 2013 by Gengkev (talk | contribs)

All 20 diagonals are drawn in a regular octagon. At how many distinct points in the interior of the octagon (not on the boundary) do two or more diagonals intersect?

$\textbf{(A)}\ 49\qquad\textbf{(B)}\ 65\qquad\textbf{(C)}\ 70\qquad\textbf{(D)}\ 96\qquad\textbf{(E)}\ 128$

Solution

70-5-16=49, so THE ANSWER IS A

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