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Loser66
 one year ago
I don't understand. Please, help
How many diagonals are there in a polygon with 9 sides?
The answer is 36
Loser66
 one year ago
I don't understand. Please, help How many diagonals are there in a polygon with 9 sides? The answer is 36

This Question is Closed

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0With 9 nodes, we pick 2 nodes to form a diagonal, hence there is 9C2 ways to get the diagonals that is 36 ways

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0However, with the formula \(\dfrac{n(n3)}{2}\) we get \(dfrac{9(93)}{2}=27\) :(

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1There are n vertices. You can choose n3 other vertices to make a segment. You cannot choose the two neighboring vertices or the original vertex itself. That's why the "n3" is there

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1the /2 portion is to correct for double counting

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0But the 2 answers didn't match. The first one is 36, the second one is 27 , how?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.136 is incorrect. It must be a typo

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1If it asked "how many distinct line segments can be formed with 9 points?", then the answer would be 36

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0question 3 http://www.testpreppractice.net/practicetests/problemsolvingsm/pssm1.html?testname=GRE

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1maybe instead of diagonals, they just meant how many segments were possible

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0They confuse me a lot. I interpreted it as above, we pick 2 vertices to form a diagonal, hence 9C2 is what they did. But the formula on your site tells me other thing. That's why I make question here. One more thing, 9C2 is a valid logic, right?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.1or maybe they redefined "diagonal", but that doesn't make much sense really

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0Ok, let me try on smaller number of sides of a polygon. Thanks for clarifying it.

Loser66
 one year ago
Best ResponseYou've already chosen the best response.0Yes, I think your site is better, just look at a rectangular. Obviously it has 2 diagonals, but if 4C2 = 6 which is total segments on a rectangular, hhehehe.!!!
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