Poly Trolly
A polygon of n sides has 275 diagonals then the number of sides is:
The answer is 25.
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3 solutions
2 n ( n − 3 ) = 2 7 5 �� n 2 − n − 5 5 0 = 0 therfore, n 2 − 2 5 n + 2 2 n − 5 5 0 = 0 n ( n − 2 5 ) + 2 2 ( n − 2 5 ) = 0 ( n − 2 5 ) ( n + 2 2 ) = 0 n = 2 5 ( o r ) n = − 2 2 Since number of diagonals cannot be negative. So, number of Diagonals is 2 5
i torgot to divide by two
correct answer but wrong solving. finding the roots of the above quadratic equation will give surds
how on earth????
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yeah i have made a mistake the formula is wrongly typed it is
for finding the number of diagonals in an n-sided polygon is 2 n ( n − 3 ) solving gives 25
and thus by solving it further you will get the answer...
the formula for finding the number of diagonals in an n-sided polygon is n(n-3)/2 solving gives 25
Wondering how the formula rose up? Well, in a polygon, you have n vertices. If you are constructing lines with these vertices, you then have nC2 possible lines that you can draw. But, we need only diagonals, so subtract the n sides from this total number of lines. Thus the total diagonals in a polygon of side n is nc2 - n. This is nothing but, (n(n-1)/2) - n . You solve this and will end up with the magical equation n(n-3)/2!!!! there you go :)