An -gon is a regular polygon with equal sides. Find the number of diagonals (edges of an -gon are not considered as diagonals) of a -gon.
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DSE 2012 Question 13: Combinatorics and counting
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An n -gon is a regular polygon with n equal sides. Find the number of diagonals (edges of an n -gon are not considered as diagonals) of a 10 -gon. (A) 20 diagonals (B) 25 diagonals (C) 35 diagonals (D) 45 diagonals
Combinatorics and counting has come up 24 times in 5 exams since 2009.
What this question tests
This question is on Permutations and combinations, part of Combinatorics and counting in Mathematics.
Counting arrangements and selections, with and without restrictions.
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Question from the DSE 2012 paper. Solutions are TestStop's own. Not affiliated with or endorsed by any examination authority.