Question 1076154
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The number of diagonals of a convex n-sided polygon is {{{(n*(n-3))/2}}}.


To answer the question, you need to solve the equation


{{{(n*(n-3))/2}}} = 12.


--->  n*(n-3) = 24 --->  n^2 - 3n - 24 = 0  --->    


--->  there is NO integer solution.


--->  Your formulation is wrong. There is no such a polygon.
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