You can put this solution on YOUR website! How many diagonals does a 30-sided polygon have?
How do you find a formula to solve this?
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If you know something about combinations the number
of pairs of points is 30C2=[30)(29)/2]=15(29)=435
But 30 of those pairs form the sides of the polygon
So the # of diagonals is 435-30=405
Try this on smaller polygons.
For example how about a pentagon
5C2-5 = [5*4/2]-5 sides = 10-5=5 diagonals
A formula would look like nC2 - n = [(n)(n-1)/2 -n] or (n^2-3n)/2
Cheers,
Stan H.
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